System option modes (SOMs)

Mode 15 = ON (default):

• Upper limit for retry of drive is reduced from 2 sec. to 0.5 sec.
• If a drive failure occurs in read processing, a correction read processing is executed immediately.
• I/O watching time is changed from 6.5 sec. to 4.5 sec. (I/O watching time including DMA transfer is 10 sec.)
• Read or write processing is not retried for time-out failure.

Mode 15 = OFF:

• Upper limit for retry of drive is 2 sec.
• If a drive failure occurs in read processing, a retry processing corresponding to the type of failure is executed.
• I/O watching time is 6.5 sec. (I/O watching time including DMA transfer is 10 sec.)
• Read or write processing is retried for time-out failure.

Notes:

1. The mode applies at a site where drive response delay may affect business operations.
2. When Dynamic Sparing or Auto Correction Mode is used, because host I/Os conflict with copy processing, the I/O watching time is 30 seconds even when this SOM is set to ON.
3. Even though SOM 15 is set to ON, the function does not apply to SATA or NL-SAS drives.
4. When SOM 771 or SOM 797 is set to ON, the setting of SOM 771/797 is prioritized for the read I/O watching time.
5. For additional details about this SOM, contact customer support (see SOM015 sheet).

Mode 22 = ON: If ECCs/LRC PINs (up to 64) have been set on the track of copy source HDD, ECCs/LRC PINs (up to 64) will be created on the track of copy target HDD so that the copy processing will continue. If the number of ECCs/LRC PINs exceeds 64, the corresponding copy processing will be interrupted.

Mode 22 = OFF (default): If ECCs/LRC PINs have been set on the track of copy source HDD, the copy processing will be interrupted. (First recover ECCs/LRC PINs by using the PIN recovery flow, and then perform the correction copy or the drive copy again.)

One of the controlling option for correction/drive copy.

When a command issued to a drive turns to time-out, the failure is counted on the failure counter of the drive port. If the failure counter reaches the port blockage threshold, the drive port is blocked. By setting the mode to ON, the port is blocked when the number of failures reaches the half point of the threshold, which mitigates the occurrence possibility of the host time-out.

Mode 142 = ON (default): The threshold value of blocking a drive port due to command time-out is changed to half of the normal threshold.

Mode 142 = OFF: The threshold value of blocking a drive port due to command time-out does not change.

Notes:

1. This SOM should always be set to ON. This SOM can be set to OFF only when the customer does not allow to set this SOM to ON for a storage system already in production.
2. Settings of SOM 363, SOM 365, and SOM 809 are related each other. The order of priority for the setting to be enabled is SOM 809, SOM 363, SOM 365, and then SOM 142. For details, contact customer support (see the mode document of each SOM).

1. Normal response delay detection logic

   Mode 144 = ON: When a response delay drive is detected, SSB=A4CE and A4DE are logged, the drive with response delay is blocked, and SSB=AE4A and SIM=EF0XXX or EF1XXX are reported.

   The behavior varies depending on the combinations of SOM settings. For details, contact customer support (see SOM144 sheet).

   Mode 144 = OFF (default 93-03-01 and later): When a response delay drive is detected, SSB=A4CE and A4DE are logged, and SIM=DFFXXX is reported.

   The behavior varies depending on the combinations of SOM settings. For details, contact customer support (see SOM144 sheet).

2. Early response delay detection logic

   When the logic that detects a minor drive response delay early, which is enabled or disabled by setting SOM 1068 to ON or OFF, detects a drive response delay, the drive with response delay is blocked.

   SOM 144 works with the logic and determines whether to block a drive or not when the logic detects a response delay.

   Mode 144 = ON: When a response delay is detected by the logic, SSB=A4CF, A4DD, and A4DE are logged, the drive with response delay is blocked, and then SSB=AE4A and SIM=EB0XXX, EB1XXX, EB2XXX, or EB3XXX is reported.

   The behavior varies depending on the combinations of SOM settings. For details, contact customer support (see sheet SOM144).

   Mode 144 = OFF (default 93-03-01 and later): When a response delay is detected by the logic, SSB=A4CF is logged and SIM=DFFXXX is reported.

   The behavior varies depending on the combinations of SOM settings. For details, contact customer support (see sheet SOM144).

Note: The mode is applied if a stable host response is prioritized by separating a drive whose response is permanently delayed at early stage when the drive delay is detected. To apply the mode, note that separating the drive causes decrease in redundancy.

Mode 164 = OFF (default): Write through operation and IO multiple-operation prevention are performed when CM/SM is blocked or in transition to blockade status.

Notes:

1. Data is not secured at the failure on both sides of CM/SM. Recovery from all volume backups is required.
2. Determine whether to set the mode to ON or OFF on the following basis:

   OFF: The mode is set to OFF to secure the data even when a CM/SM dual failure occurs. As the write through works for data assurance at CM/SM one-side blockage, make sure to design a system where performance degradation such as I/O response is acceptable in a configuration where data from host is duplicated on primary and secondary storages.

   ON: The mode is set to ON to prioritize maintaining the performance over data assurance as a single storage system when a CM/SM dual failure occurs. When the mode is set to ON, the data may be lost at the CM/SM dual failure. If high data reliability is required for the storage system like RAID, data duplication should be realized by the entire system like a configuration where data from host is duplicated on primary and secondary storages.

3. Using the mode poses a risk of losing the data at a CM/SM dual failure. If high data reliability is required for the storage system like RAID, data duplication should be realized by the entire system like the configuration where data from host is duplicated on primary and secondary storages.
4. When the mode is used, the time required for blocking cache memory/shared memory at maintenance is longer than that when the mode is set to OFF so that the maintenance operation may end abnormally if the amount of write pending is large. Therefore, perform the maintenance operation when the amount of write pending is as less as possible. If the maintenance operation ends abnormally, replace the blocked part to recover.
5. When setting the function to each LDEV is desired, see "WR Through" function on the System Option window. See 2.13 System option in the SVP section of the Maintenance Manual. Also, follow the above (1) even when the "WR Through" is used.

Mode 310 = ON: The monitoring timer for MP hang-up is 6 seconds and returning a response to the host within 8 seconds is guaranteed.

Mode 310 = OFF (default): The monitoring timer for MP hang-up is 8 seconds.

Notes:

1. This SOM applies to a site where strict host response performance is required.
2. If a hardware failure occurs when this SOM is set to ON, the time until MPB blockage is determined is shorter than usual.

Mode 448 = OFF (default): After a physical path failure (such as path disconnection) is detected, a mirror is split (suspended) if the path is not restored within the path monitoring time set by the mirror option.

Notes:

1. The mode is applied when a user requires to suspend the pair one minute after a communication error between UR MCU and RCU is detected.
2. When SOM 449 is set to ON, SOM 448 does not function.

Mode 449 = ON (default): When a physical path failure is detected, the pair is not suspended. On the MCU side, checking read journal command disruption from the RCU is disabled, and monitoring read journal command failures is disabled on the RCU side.

Mode 449 = OFF: When a physical path failure is detected, the pair is suspended after the path monitoring time set by the mirror option has passed or after one minute. Detecting communication failures between the MCU and RCU is enabled. When this mode is set to OFF, SOM 448 can be enabled.

Notes:

1. This SOM is applied when disabling the detection of communication failures between the MCU and RCU in UR configuration is required.
2. When this SOM is set to ON, SOM 448 does not work.
3. This SOM setting is not changed by microcode upgrade.
4. This SOM is not effective for remote paths between an Initiator port on the MCU and a Target port on the RCU.
5. While a path from the RCU to MCU is disconnected, if the UR pair remains in Suspending or Deleting status, consult the troubleshooting information in the Hitachi Universal Replicator User Guide. If you are not able to resolve the error condition, contact customer support.

Mode 454 = OFF (default): The amount of the entire destage processing is periodically determined by using the highest workload of all CLPRs (*a). (The larger the workload is, the larger the amount of the entire destage processing becomes.)

*a: (Write Pending capacity of CLPR#x of concerned MPB) ÷ (Cache capacity of CLPR#x of concerned MPB), x=0 to 31

CLPR whose value above is the highest of all CLPRs

Because the destage processing would be accelerated depending on CLPR with high workload, when the workload in a specific CLPR increases, the risk of host I/O halt would be reduced.

Therefore, set SOM 454 to OFF in most cases.

Mode 454 = ON:

The amount of the entire destage processing is periodically determined by using the workload of the entire system (*b). (The larger the workload is, the larger the amount of the entire destage processing becomes.)

*b: (Write Pending capacity of the entire system of concerned MPB) ÷ (Cache capacity of the entire system of concerned MPB)

Caution: Because the destage processing would not be accelerated even if CLPR has high workload, when the workload in a specific CLPR increases, the risk of host I/O halt would be increased. Therefore, set SOM 454 to ON only when a CLPR has constant high workload and the I/O performance in a CLPR with low workload has higher priority than host I/O halt in the CLPR with high workload.

Notes:

1. When this SOM is set to ON, even if there is an overloaded CLPR (CLPR with large Write Pending capacity), the amount of destage processing would not increase easily. Therefore TOV(MIH) may occur in the overloaded CLPR. Set this SOM to ON only when the overloaded state of a specific CLPR would not affect other CLPRs.

   When the UR function is used, if user volumes and journal volumes are defined in different CLPRs, when the CLPR to which the journal volumes are assigned overflows, the user volumes become inaccessible. Therefore it is recommended to set this SOM to OFF.

2. Because the destage processing will have a lower priority in the overloaded CLPR, the overloaded state of the overloaded CLPR is not removed, and TOV(MIH) might occur.

High-speed LDEV format for external volumes

Mode 457 = ON: When you select an external volume group and perform LDEV format, any write processing on the external LUs will be skipped. However, if the external LDEV is a mainframe volume, the Write processing for mainframe control information only will be performed after the write skip.

Mode 457 = OFF (default): High-speed LDEV format for external volumes is not available.

Notes:

• If the LDEV is not written with data "0" before performing the function, the LDEV format might fail.
• After the format processing, make sure to set SOM 457 to OFF.

The pair status changes to PSUS when the destaging is complete. When a split operation is performed for an SI pair, the pair status changes from PAIR to PSUS(SP) or COPY(SP) (status transition period), and then to PSUS.

The function works during the status transition period.

Mode 459 = ON (default): The pair stays in the status transition period and waits for the destaging to be complete.

Mode 459 = OFF: Immediately after all differential data is copied to cache, the pair status changes to PSUS.

The pair does not stay in the status transition period to wait for the destaging to be complete.

Notes:

1. Apply the mode for users who require that de-staging S-VOL data to an external volume mapped to the S-VOL has been completed when the pair status changes to PSUS.
2. The function works for the pairs created while the mode is set to ON and does not work for the pairs created while the mode is set to OFF.
3. Because de-staging takes place after the copy is complete, the time required to change the status from PSUS(SP) or COPY(SP) to PSUS increases.
4. When both SOM 459 and SOM 1263 are used, the throughput improvement by setting SOM 1263 to ON cannot be expected.
5. At a split operation, the time required to change the status to PSUS when the mode is ON gets longer than that when the mode is set to OFF.

Universal Volume Manager

Volume Migration

• SI
• UVM
• VM

Mode 467 = ON (default): The copy processing stops if the dirty percentage is 60% or larger. If the dirty percentage becomes lower than 60%, the copy processing restarts.

Mode 467 = OFF: The copy processing slows down if the dirty percentage is 60% or larger, and it stops if the dirty percentage is 75% or larger.

Notes:

1. This SOM must always be set to ON when using an external volume as the secondary volume of any of the applicable replication products.
2. It takes longer to finish the copy processing because it stops for prioritizing the host I/O performance.
3. This SOM supports background copy only. The processing to copy the pre-update data to the S-VOL, which occurs when overwriting data to uncopied slots of P-VOL in Split processing or reading or writing data to uncopied slots of S-VOL, is not supported.
4. Check the write pending rate of each CLPR per MP unit. Even though there is some free cache capacity in the entire system, if the write pending rate of an MP unit to which SI orVM pairs belong exceeds the threshold, the copy operation is stopped.

The SIM-RCs reported by setting the SOM to ON are: 601xxx (Pool utilization threshold exceeded), 603000 (SM space warning).

Mode 471 = ON: These SIMs are reported to maintenance personnel.

Mode 471 = OFF (default): These SIMs are not reported to maintenance personnel.

Note: Set this SOM to ON when it is required to inform maintenance personnel of these SIM-RCs.

Mode 474 = ON: For a suspended UR pair, a TC (Sync) pair can be created with the same P-VOL/S-VOL so that UR initial copy time can be reduced by using the dedicated script.

Mode 474 = OFF (default): For a suspended UR pair, a TC (Sync) pair cannot be created with the same P-VOL/S-VOL. For this, the dedicated script cannot be used.

When the P-VOL and S-VOL are both DP-VOLs, initial copy performance might not improve with SOM 474 set to ON. This is because with DP-VOLs, not all areas in the volume are allocated for UR; therefore, not all areas in the P-VOL are copied to the S-VOL. With less than the full amount of data in the P-VOL being copied, the initial copy completes in a shorter time, which might not be improved with SOM 474.

Notes:

1. Set this SOM for both primary and secondary storage systems.
2. When this SOM is set to ON:
   • Execute all pair operations from CCI.
   • Use a dedicated script.
   • Initial copy operation is prioritized over update I/O. Therefore, the processing speed of the update I/O slows down.
3. If this SOM is set to ON, the processing speed of update I/O slows down by about 15 μs per command, version downgrade is disabled, and Take Over is not available.
4. If this SOM is not set to ON for both sides, the behavior is as follows:
   • OFF in primary and secondary storage systems: Normal UR initial copy performance.
   • ON in the primary storage system/OFF in the secondary storage system: TC Sync pair creation fails.
   • OFF in the primary storage system/ON in the secondary storage system: The update data is copied to the S-VOL synchronously.
5. While this SOM is set to ON, make sure not to perform microcode downgrade to an unsupported version.
6. While this SOM is set to ON, make sure not to perform the Take Over function.
7. This SOM cannot be applied to a UR pair that is the second mirror in a URxUR multi-target configuration, URxUR cascade configuration, or 3DC multi-target or cascading configuration of three UR sites. If applied, TC pair creation is rejected with SSB=CBED output.
8. Before setting SOM 474 to ON, make sure that SOM 1091 is set to OFF. If SOM 1091 is set to ON, set it to OFF first, and then set SOM 474 to ON.

The UR delta resync configuration is required.

Mode 506 = ON (default):

• Without update I/O: Delta resync is enabled.
• With update I/O: Delta resync is enabled.

Mode 506 = OFF:

• Without update I/O: Total data copy of delta resync is performed.
• With update I/O: Delta resync is enabled.

Note: Even when SOM 506 is set to ON, the delta resync may fail and only the total data copy of the delta resync function is allowed if the necessary journal data does not exist on the primary storage system used for the delta resync operation.

Mode 556 = ON: An error code is not set in bytes 8 - 11 in the standard 16-byte sense byte.

Mode 556 = OFF (default): An error code is set in bytes 8 - 11 in the standard 16-byte sense byte.

Mode 589 = ON: For each external volume, progress is updated only when the progress rate is 100%.

Mode 589 = OFF (default): Progress is updated when the progress rate exceeds the previous level.

Notes:

1. Set this SOM to ON when disconnecting an external volume while the specific host IO operation is online and its performance requirement is severe.
2. Whether the disconnecting status for each external volume is progressed or not cannot be confirmed on Device Manager - Storage Navigator (it indicates "-" until just before the completion and at the last it changes to 100%).

Mode 624 = ON: If 5 minutes have passed after time stamp update from CCI stops (*), pairs of journal groups on the storage systems with the mode set to ON are suspended due to failure (SIM=DC1XYY ).

* The reason of the stop is unstable path status between the CCI server and the storage system in the primary site, or a stop of a CCI instance.

Mode 624 = OFF (default): Pair are not suspended due to failure 5 minutes after time stamp update from CCI stops.

Notes:

1. Apply the mode if suspending pairs, preventing journals from being accumulated, and notifying the error to users are preferred rather than allowing journal accumulation and eventual failure suspension due to journal full when the communication between CCI and the storage system in the primary site is unavailable in a consistency group configuration.
2. When the mode is set to ON, set the interval of issuing time stamps from CCI to 4 minutes or less. (About 1 second is recommended). If greater than 4 minutes is set, the function may work 5 minutes after a temporary communication error, etc.
3. To stop a CCI instance for 5 minutes or longer for CCI configuration definition file rewriting or server maintenance, set the mode to OFF.
4. If the DKCMAIN microcode is downgraded to an unsupported version while the mode is set to ON, and then the microcode is to be upgraded to the supported version, set the mode to OFF before the microcode upgrade.

Global-active device

Mode 689 = ON: The initial copy and resync copy operations are slowed down when the Write Pending rate on RCU exceeds 60%.

If the CLPR write pending rate where the initial copy target secondary volume belongs to is not over 60% but that of MP PCB where the S-VOL belongs to is over 60%, the initial copy operation is slowed down.

Mode 689 = OFF (default): The initial copy and resync copy operations are not slowed down when the Write Pending rate on RCU exceeds 60% (the same as before).

Notes:

1. This SOM can be set online.
2. The micro-programs on both MCU and RCU must support this SOM.
3. This SOM should be set when requested by the user.
4. Setting this SOM to ON is recommended when GAD is installed, as the performance degradation is more likely to occur due to active-active I/Os.
5. If the write-pending status remains at 60% or higher on the RCU for a long time, it takes extra time for the initial copy and resync copy to be completed due to the slower copy operations.
6. If the write pending rate of CLPR to which the initial copy target S-VOL belongs is not over 60% but that of MP PCB to which the S-VOL belongs is over 60%, the initial copy operation is slowed down.
7. As the mode is enabled per DKC, in an environment where TC and GAD are used, the mode is applied to both program products. When GAD is installed in a storage system that already uses TC, TC initial copy might take longer time.

• When CLPR of JNL-Volume exceeds 60%, Read JNL is prevented.
• When CLPR of Data (secondary)-Volume exceeds 60%, JNL Restore is prevented.

Mode 690 = ON: Read JNL or JNL Restore is prevented when the Write Pending rate on RCU exceeds 60%.

Mode 690 = OFF (default): Read JNL or JNL Restore is not prevented when the Write Pending rate on RCU exceeds 60% (the same as before).

Notes:

1. This SOM can be set online.
2. This SOM should be set per customer’s requests.
3. If the Write Pending status long keeps 60% or more on RCU, it takes extra time for the initial copy to be completed by making up for the prevented copy operation.
4. If the Write Pending status long keeps 60% or more on RCU, the pair status may become Suspend due to the JNL-Vol being full.

Mode 701 = ON: The Read command is issued at the logical unit discovery operation.

Mode 701 = OFF (default): The Read command is not issued at the logical unit discovery operation.

Notes:

1. When this SOM is set to ON, it takes longer time to complete the LU discovery. The amount of time depends on external storages.
2. With this SOM OFF, if searching for external devices with VMA is set, the VMA information cannot be read.
3. When this SOM is set to ON while the following conditions are met, the external volume is blocked:
   • An external volume to which Nondisruptive migration (NDM) attribute is set exists.
   • The external volume is reserved by the host
4. As the VMA information is USP/NSC specific, this mode does not need to be ON when the external storage is other than USP/NSC.
5. Set this SOM to OFF when an external volume to which nondisruptive migration (NDM) attribute is set exists.

Volume Migration

Mode 704 = ON: Copy processing requested is registered into a newly created queue so that the processing is scheduled with lower priority than host I/O.

Mode 704 = OFF (default): Copy processing requested is not registered into a newly created queue. Only the existing queue is used.

Notes:

1. Apply this SOM when the load of host I/O to an ECC that uses ShadowImage or Volume Migration is high and the host I/O processing is delayed.
2. If the PDEV is highly loaded, the priority of Read/Write processing made by ShadowImage, Volume Migration, or Resync may become lower. As a consequence the copy speed may be slower.

Mode 721 = ON: When a parity group is uninstalled or installed, the LED of the drive for uninstallation is not illuminated, and the instruction message for removing the drive does not appear. Also, the windows other than that of parity group, such as DKA or DKU, are unavailable to select.

Mode 721 = OFF (default): When a parity group is uninstalled or installed, the operation is as before: the LED of the drive is illuminated, and the drive must be unmounted and remounted.

Notes:

1. When the RAID level or emulation type is changed for the existing parity group, this SOM should be applied only if the drive mounted position remains the same at the time of the parity group uninstallation or installation.
2. After the operation using this SOM is completed, this SOM must be set back to OFF; otherwise, the LED of the drive to be removed will not be illuminated at subsequent parity group uninstalling operations.

Mode 725 = ON: When Not Ready is returned, the external path is blocked and the path status can be automatically recovered (Not Ready blockade). Note that the two behaviors, automatic recovery and block, may be repeated.

When the status of a device is Not Ready blockade, Device Health Check is executed after 30 seconds.

For the device of Not Ready blockade, the Device Health Check is executed after 30 seconds.

Mode 725 = OFF (default): When Not Ready is returned three times in three minutes, the path is blocked and the path status cannot be automatically recovered (Response error blockade).

Notes:

1. Applying this SOM is recommended when SUN storage is used as an external storage.
2. Applying this SOM is recommended if a maintenance operation such as firmware update causing controller reboot is executed on the external storage side while a storage system other than Hitachi product is used as an external storage system.

Data Retention Utility

Mode 729 = ON: To set the Protect attribute for the target DP-VOL using the DRU, when any Write operation is requested to the area where the page allocation is not provided at a time when the DP Pool is full. (Not to set in the case of Read request.)

Mode 729 = OFF (default): Not to set the Protect attribute for the target DP-VOL using the DRU, when any Write operation is requested to the area where the page allocation is not provided at a time when DP Pool is full.

For details, contact customer support (see SOM729 & 803 sheet).

Notes:

1. This SOM is applied when:
   • The threshold of pool is high (for example, 95%) and the pool may be full.
   • DP-VOL uses file system is used.
   • Data Retention Utility is installed.
2. Since the Protect attribute is set for V-VOL, the Read operation cannot be allowed as well.
3. When Data Retention Utility is not installed, the desired effect is not achieved.
4. Protect attribute can be released from the Data Retention window of Device Manager - Storage Navigator after releasing the full status of the pool by adding a Pool-VOL.
5. The Virtual Volume Protection (VVP) function can be enabled/disabled for each pool. With SOM 729 disabled, VVP is also disabled by default, but you can enable VVP for each pool as needed. With SOM 729 enabled, VVP is also enabled automatically (by default) when you create a new pool. Caution: A pool is NOT protected by ANY FUNCTION if you deliberately turn VVP for the pool from ON (default) to OFF, even with SOM 729 enabled.
6. When HMO 63 or 73 is set to ON, the setting of the HMO is prioritized over the SOM 729 setting, so that the behavior remains the same as when SOM 729 is OFF even when it is set to ON.

SIM-RC 625000 (DP pool usage rate continues to exceed the threshold).

Mode 741 = ON: SIM is reported to the service personnel.

Mode 741 = OFF (default): SIM is not reported to the service personnel.

Notes:

1. This SOM is set to ON to have SIM for users reported to the service personnel:
   • For the system where SNMP and E-mail notification are not set.
   • If Device Manager - Storage Navigator is not periodically activated.
2. When SOM 734 is turned OFF, SIM-RC625000 is not reported; accordingly the SIM is not reported to the service personnel even though this SOM is ON.

Notes:

1. This option is set to ON to have SIM for users reported to the service personnel for the system where SNMP and E-mail notification are not set or if Device Manager - Storage Navigator isn’t periodically activated.
2. When SOM 734 is OFF, SIM-RC625000 is not reported; accordingly the SIM is not reported to the service personnel even though this SOM 741 is ON.

Mode 745 = ON:

• The area where the information is obtained as the Characteristic1 item from SYMMETRIX is changed.
• When CheckPaths or Device Health Check (1/hour) is performed, the information of an already-mapped external volume is updated to the one after change.

Mode 745 = OFF (default):

• The area where the information is obtained as the Characteristic1 item from SYMMTRIX is set to the default.
• When CheckPaths or Device Health Check (1/hour) is performed, the information of an already-mapped external volume is updated to the default.

Notes:

1. This SOM is applied when the EMC SYMMETRIX is connected using UVM.
2. Enable the setting of EMC SCSI Flag SC3 for the port of the EMC SYMMETRIX storage connected with the storage system and disable the setting of Flag SPC2. If the setting of EMC SCSI Flag SC3 is not enabled or the setting of Flag SPC2 is enabled, the effect of this SOM may not be achieved.
3. If you want to enable this SOM immediately after setting, perform Check Paths on each path one by one for all the external ports connected to the EMC SYMMETRIX storage. But, without doing Check Paths, the display of Characteristic1 can automatically be changed by the Device Health Check to be performed once an hour. If SSB=AD02 occurs and a path is blocked, perform Check Paths on this path again.

Dynamic Tiering

Mode 749 = ON: The DP Rebalance function and the DT Tier relocation function are disabled.

Mode 749 = OFF (default): The DP Rebalance function and the DT Tier relocation function are enabled.

Notes:

1. This SOM is applied when no change in performance characteristic is desired.
2. When a pool is newly installed, the load may be concentrated on the installed pool volumes.
3. When 0 data discarding is executed, load may be unbalanced among pool volumes.
4. Pool-VOL deletion while this SOM is set to ON fails. To delete pool-VOLs, set this SOM to OFF.

Mode 757 = ON: In-band audit log is not output.

Mode 757 = OFF (default): In-band audit log is output.

Notes:

1. Mode 757 applies to the sites where outputting the In-band audit logs is not needed.
2. When this SOM is set to ON:
   • There is no access to SM for the in-band audit logs, which can avoid the corresponding performance degradation.
   • SM is not used for the in-band audit logs.
3. If outputting the in-band audit log is desired, set this SOM to OFF.

Global-active device

This SOM is applied to TC and GAD. This SOM supports paths between DKCs using Fibre, but not those between DKCs using iSCSI.

Mode 784 = ON: The MIH time of RIO is internally reduced so that, even though a path failure occurs between storage systems in the environment where host MIH time is set to 15 seconds, update I/Os can be processed by using an alternate path promptly, lowering the possibility of host MIH occurrence.

Mode 784 = OFF (default): The operation is processed in accordance with the TC or GAD specification.

Notes:

1. This SOM is applied to the environment where OPEN host time-out time is set to 15 seconds or less.
2. This SOM is applied to reduce RI/O MIH time to 5 seconds.
3. This function is available for all the TC and GAD pairs on the storage system, unable to specify the pairs that are using this function or not.
4. For a TC or GAD pair with this SOM effective (RI/O MIH time is 5 seconds), the setting of RI/O MIH time made at RCU registration (default is 15 seconds, which can be changed within range from 10 to 100 seconds) is invalid. However, RI/O MIH time displayed on Device Manager - Storage Navigator and CCI is not "5 seconds" but is what set at RI/O registration.
5. If a failure occurs on the switched path between storage systems, Mainframe host MIH or Open server time-out may occur.
6. If an MP to which the path between storage systems belongs is overloaded, switching to an alternate path delays and host MIH or time-out may occur.
7. If an RI/O retry occurs due to other factors than RI/O MIH (5 sec), such as a check condition report issued from RCU to MCU, the RI/O retry is performed on the same path instead of an alternate path. If a response delay to the RI/O occurs constantly on this path due to path failure or link delay, host MIH or time-out may occur due to response time accumulation for each RI/O retried within 5 seconds.
8. Even though this SOM is set to ON, if Mainframe host MIH time or Open host time-out time is set to 10 seconds or less, host MIH or time-out may occur due to a path failure between storage systems.
9. Operation commands are not available for promptly switching to an alternate path.
10. This SOM works for the pair for which initial pair creation or Resync operation is executed.
11. Micro-program downgrade to an unsupported version cannot be executed unless all the TC and GAD pairs are suspended or deleted.
12. For operational specifications in each combination of MCU and RCU of TC, contact customer support (see SOM784 sheet).
13. For GAD pairs, this SOM is effective if the microcode version supports GAD.
14. This SOM does not support iSCSI paths between storage systems. When iSCSI is used for paths between storage systems, the time to switch to an alternate path cannot be reduced. For this, if a failure occurs on a path between storage systems in an environment where host time-out time is short, a time-out may occur on the host side. A time-out may also occur on the host side when a failure occurs on an iSCSI path between storage systems if storage system paths of Fibre and iSCSI coexist in an environment where host time-out time is short so that the configuration where storage system paths of Fibre and iSCSI coexist is not supported too.

Data Retention Utility

Mode 803 = ON: While a DP pool-VOL is blocked, if a read or write I/O is issued to the blocked pool-VOL, the DRU attribute is set to Protect.

Mode 803 = OFF (default): While a DP pool-VOL is blocked, if a read or write I/O is issued to the blocked pool-VOL, the DRU attribute is not set to Protect.

For details, contact customer support (see SOM729 & 803 sheet).

Notes:

1. This SOM is applied when:
   • A file system using DP pool-VOLs is used.
   • Data Retention Utility is installed.
2. Because the DRU attribute is set to Protect for the V-VOL, a read I/O is also disabled.
3. If Data Retention Utility is not installed, the expected effect cannot be achieved.
4. The Protect attribute of DRU for the DP V-VOL can be released on the Data Retention window of Device Manager - Storage Navigator after recovering the blocked pool-VOL.
5. The Virtual Volume Protection (VVP) function can be enabled/disabled for each pool. With SOM 803 disabled, VVP is also disabled by default, but you can enable VVP for each pool as needed. With SOM 803 enabled, VVP is also enabled automatically (by default) when you create a new pool.

   Caution: A pool is NOT protected by ANY FUNCTION if you deliberately turn VVP for the pool from ON (default) to OFF, even with SOM 803 enabled.

Volume Migration

Mode 855 = ON: When the amount of dirty data is within the range from 58% to 63%, the next copy processing is continued after the dirty data created in the previous copy is cleared to prevent the amount of dirty data from increasing (copy after destaging). If the amount of dirty data exceeds 63%, the copy processing is stopped.

Mode 855 = OFF (default): The copy processing is stopped when the amount of dirty data is over 60%.

For details, contact customer support (see SOM855 sheet).

Notes:

1. This SOM is applied when all the following conditions are met
   • ShadowImage is used with SOM 467 set to ON.
   • Write pending rate of an MP unit that has LDEV ownership of the copy target is high
   • Usage rate of a parity group to which the copy target LDEV belongs is low.
   • ShadowImage copy progress is delayed.
2. This SOM is available only when SOM 467 is set to ON.
3. If the workload of the copy target parity group is high, the copy processing may not be improved even if this SOM is set to ON.

Dynamic Tiering

Mode 867 = ON: LDEV format of the DP-VOL is performed with page reclamation.

Mode 867 = OFF (default): LDEV format of the DP-VOL is performed with 0 data writing.

Notes:

1. The mode is applied when a customer requires disabling the background format for a DP/DT/TI*2 pool due to a concern of performance degradation of other functions in an environment where a DP-VOL is used by other functions.
2. When the background format function is enabled, because up to 42 MB/s of ECCG performance is used, local copy performance might degrade by about 10%. Therefore, confirm whether the 10% performance degradation is acceptable or not before enabling the function.
3. When a DP-VOL on an external storage system, which is used as an external VOL, is used as a pool-VOL, if the external pool on the external storage side becomes full due to the background format, the external VOL might be blocked.

   If the external pool capacity is smaller than the external VOL capacity (DP-VOL of external storage system), do not enable the background format function.

4. If the background format function is disabled by changing the mode setting, the format progress is initialized and the entire area becomes unformatted.

Dynamic Tiering

Thin Image

For information regarding operating conditions, see the Provisioning Guide.

Mode 896 = ON: The background format function is disabled.

Mode 896 = OFF (default): The background format function is enabled.

Notes:

1. This SOM is applied when you need to disable the background format for a DP/DT/TI pool due to a concern of performance degradation of other functions in an environment where a DP-VOL is used by other functions.
2. When the background format function is enabled, because up to 42 MB/s of ECCG performance is used, local copy performance may degrade by about 10%. Therefore, confirm whether the 10% performance degradation is acceptable or not before enabling the function.
3. When a Dynamic Provisioning VOL on an external storage system, which is used as an external VOL, is used as a pool VOL, if the external pool on the external storage side becomes full due to the background format, the external VOL may be blocked.

   If the external pool capacity is smaller than the external VOL capacity (Dynamic Provisioning VOL of external storage system), do not enable the background format function.

4. If the background format function is disabled by changing this SOM setting, the format progress is initialized and the entire area becomes unformatted.

Mode 899 = ON (default):

• SOM 900 is ON: I/O synchronous copy starts without retrying Volume Migration.
• SOM 900 is OFF: I/O synchronous copy starts when the threshold of Volume Migration retry is exceeded. (Recommended.)

Mode 899 = OFF:

• SOM 900 is ON: I/O synchronous copy starts when the number of retries reaches half of the threshold of Volume Migration retry.
• SOM 900 is OFF: Volume Migration is retired and I/O synchronous copy is not executed.

Notes:

1. This SOM is applied when improvement of Volume Migration success rate is desired under the condition that there are many updates to a migration source volume of Volume Migration.
2. During I/O synchronous copy, host I/O performance degrades.

Mode 900 = ON:

• SOM 899 is ON: I/O synchronous copy starts without retrying Volume Migration.
• SOM 899 is OFF: I/O synchronous copy starts when the number of retries reaches half of the threshold of Volume Migration retry.

Mode 900 = OFF (default):

• SOM 899 is ON: I/O synchronous copy starts when the threshold of Volume Migration retry is exceeded. (Recommended)
• SOM 899 is OFF: Volume Migration is retired and I/O synchronous copy is not executed.

Notes:

1. This SOM is applied when improvement of Volume Migration success rate is desired under the condition that there are many updates to a migration source volume of Volume Migration.
2. During I/O synchronous copy, host I/O performance degrades.

Mode 901 = ON: For tier1 (drive type is SSD), pages are allocated until the capacity reaches the limit. Without consideration of exceeding performance limitation, allocation is done from highly loaded pages until reaching the capacity limit

When the capacity of tier1 reaches the threshold value, the minimum value of the tier range is set to the starting value of the lower IOPH zone, and the maximum value of the lower tier range is set to the boundary value.

Mode 901 = OFF (default): For tier1 (drive type is SSD), page allocation is performed based on performance potential limitation. With consideration of exceeding performance limitation, allocation is done from highly loaded pages but at the point when the performance limitation is reached, pages are not allocated any more even there is free space.

When the capacity of tier1 reaches the threshold value, the minimum value of the tier range is set to the boundary value, and the maximum value of the lower tier range is set to a value of boundary-value × 110% + 5 [IOPH].

Notes:

1. This SOM is applied when pages with the maximum capacity need to be allocated to tier1 (drive type is SSD) with Dynamic Tiering.
2. When Tier1 is SSD while SOM 901 is set to ON, the effect of SOM 897 and 898 to the gray zone of Tier1 and Tier2 is disabled and the SOM 901 setting is enabled instead. In addition, the settings of SOM 897 and 898 are effective for Tier2 and Tier3.
3. The following is recommended when applying SOM 901.

   [actual I/O value (total number of I/Os of all tiering policies)] < [performance potential value of Tier1* × 0.6]

   * The performance potential value of Tier1 displayed on Monitor information by using Dx-ray.

For more details about the interactions between SOMs 897, 898, and 901, contact customer support (see SOM897_898_901 sheet).

Mode 904 = ON: The number of pages to be migrated at tier relocation is set to up to one page per second.

Mode 904 = OFF (default):No restriction on the number of pages to be migrated at tier relocation (existing specification).

Notes:

1. This SOM is applied when the requirement for response time is severe.
2. The number of pages to be migrated per unit time at tier relocation decreases.

Mode 908 = ON: The difference in CM allocation capacity among MPBs with different workload is large.

Mode 908 = OFF (default): The difference in CM allocation capacity among MPBs with different workload is small (existing operation) .

Notes:

1. If a CLPR is used by only some MPBs among all the installed MPBs, set this SOM to ON for the CLPR to increase CM capacity allocated to the MPBs that use the CLPR.

   Example: a CLPR used only for UR JNLG

2. Since CM capacity allocated to MPBs with low load is small, the performance is affected by a sudden increase in load.
3. SOM 908 cannot be used with SOM 933. When SOM 933 is set to ON, the function of SOM 908 is canceled even though SOM 908 is ON.
4. This SOM is effective for a CLPR. Therefore, when setting this SOM to ON/OFF, select target "LPRXX (XX=00 to 31)". For example, even when CLPR0 is defined (any of CLPR1 to 31 are not defined), select "LPR00" first and then set this SOM to ON/OFF.

Dynamic Tiering

ShadowImage

* Zero data page reclamation by WriteSame and UNMAP functions, IO synchronous page reclamation, program product synchronous page reclamation, and UDSR (User Direct Space Release) are not disabled.

Mode 930 = ON: All of the zero data page reclamation operations in processing are stopped at once. (Also the zero data reclamation cannot be newly started.)

Mode 930 = OFF (default): The zero data page reclamation is performed.

For details about interactions with SOM 755, contact customer support (see SOM930 sheet).

Notes:

1. This SOM is applied when stopping or disabling zero data page reclamation by user request is required.
2. When this SOM is set to ON, the zero data page reclamation does not work at all.

   * * Zero data page reclamation by WriteSame and UNMAP, IO synchronous page reclamation, program product synchronous page reclamation, and UDSR page reclamation can work.

3. When downgrading micro-program to a version that does not support this SOM while this SOM is set to ON, set this SOM to OFF after the downgrade.

   * Because the zero data page reclamation does not work at all while this SOM is set to ON.

4. This SOM is related to SOM 755. For details, contact customer support (see SOM930 sheet).

Dynamic Tiering

Mode 937 = ON: HDT monitoring data is collected even if the pool is a DP pool.

Only Manual execution mode and Period mode are supported.

Mode 937 = OFF (default): HDT monitoring data is not collected if the pool is a DP pool

Notes:

1. This SOM is applied when HDT monitoring data collection is required in DP environment.
2. When HDT is already used, do not set this SOM to ON.
3. For HDT monitoring data collection, shared memory for HDT must be installed. For details, contact customer support (see SOM937 sheet).
4. If monitoring data collection is performed without shared memory for HDT installed, an error is reported and the monitoring data collection fails.
5. Before removing the shared memory for HDT, set this SOM to OFF and wait for 30 minutes.
6. Tier relocation with monitoring data collected when this SOM is set to ON is disabled.
7. When DP is converted into HDT (after purchase of software license), the collected monitoring data is discarded.
8. Before downgrading the micro-program to an unsupported version, set SOM 937 to OFF and wait for at least 30 minutes.

Mode 972 = ON: The THP page size is 0x200 (256KB) regardless of the SOM 973 setting.

Mode 972 = OFF (default):

• When SOM 972 is OFF and SOM 973 is ON, the THP page size is 0x10 (8KB).
• When SOM 972 and SOM 973 are both OFF, the THP page size is 0x15000 (42MB).

Notes:

1. This SOM is applied when a delay in host I/O response due to reclamation processing occurs in a customer environment.
2. Reclamation processing is delayed.
3. This SOM is to prioritize host I/O response over reclamation processing in VxVM environment, so that the time required for reclamation processing may increase when this SOM is set to ON.

For details about the interaction between this SOM and SOM 1069, contact customer support (see SOM1069 sheet).

Mode 973 = ON:

• When SOM 973 and SOM 972 are both ON, the THP page size is 0x200 (256KB).
• When SOM 973 is ON and SOM 972 is OFF, the THP page size is 0x10 (8KB).

Mode 973 = OFF (default):

• When SOM 973 is OFF and SOM 972 is ON, the THP page size is 0x200 (256KB).
• When SOM 973 and SOM 972 are both OFF, the THP page size is 0x15000 (42MB).

Notes:

1. This SOM is applied when a delay in host I/O response due to reclamation processing occurs in a customer environment.
2. When this SOM is set to ON, reclamation processing is delayed.
3. This SOM is to prioritize host I/O response over reclamation processing in VxVM environment, so that the time required for reclamation processing may increase when the mode is set to ON.

For details about the interaction between this SOM and SOM 1069, contact customer support (see SOM1069 sheet).

Mode 1015 = ON: The pair status changes to COPY and then to PAIR when a delta resync is performed in a TC-UR delta configuration.

Mode 1015 = OFF (default): The pair status changes directly to PAIR (not via COPY) in a TC-UR delta configuration.

Notes:

1. The function works by setting the mode to OFF. The mode is applied (setting to ON) when the existing delta resync function (pair status changes to COPY and then PAIR) is required
2. Set the mode on the site of TC S-VOL in TC-UR 3DC configuration. Considering site switch by delta resync, setting the mode on both TC primary and secondary sites is recommended.
3. With microcode versions including those of old models that do not support the mode, even if the mode is set to OFF on L site of TC-UR delta configuration, the behavior does not change but the status changes to COPY and then the delta resync is complete.
4. Regardless of remote command device setting, the copy status does not change to COPY and then the delta resync is complete
5. If a delta resync fails, all-data copy works. In this case, the pair status changes to COPY and then the delta resync is complete even when the mode is set to OFF.
6. When the mode setting is default (OFF), a delta resync operation is complete without pair status change to COPY. Therefore, if an operation at a customer site has to wait until the pair status changes to COPY, such as running pairevtwait of CCI, set the mode to ON.
7. When the mode setting is default (OFF), delta resync is complete without pair status change to COPY so that SIMs and SSBs reported due to pair status change to COPY are not reported.
8. Setting change to ON or OFF during delta resync is not applied. Change the mode setting prior to delta resync.
9. During delta resync, downgrading the microcode to a version that does not support the mode is disabled in TC-UR delta configuration. If microcode downgrade is disabled (FunctionID:0701) when delta resync is not in process, suspend the UR pair and then retry the microcode replacement.

Mode 1021 = ON: An external volume that is blocked due to Not Ready status can be recovered automatically regardless of the type of external storage system.

Mode 1021 = OFF (default): An external volume that is blocked due to Not Ready status might not be recovered automatically depending on the type of external storage system.

Notes:

1. This SOM is applied when the auto-recovery of external volumes that are blocked due to Not Ready status is desired in UVM connection using an ECM storage system as an external storage system.
2. When this SOM is set to ON and the connected external storage system is not in stable status (such as failure and recovery from failure), a blockage due to Not Ready status and auto-recovery might occur repeatedly.

Mode 1043 = ON: When the following conditions are met at the UR secondary site, the journal copy is disabled.

The following conditions (1) and (2) or (1) and (3) are met:

1. 4,096 or more journals are accumulated at the secondary site.
2. The CLPR write pending rate for journal volumes of the MPB/MPU where journal ownership at RCU is defined is 25% or higher (including the write pending rate for other than journal volumes).
3. It takes 15 seconds or longer to start restore after journal copy at the RCU.

Note: Even though the above conditions are met, journal copy is not disabled when all time stamps of the journals accumulated are the same in a consistency group containing multiple journals.

Mode 1043 = OFF (default): The journal copy is not disabled.

Notes:

1. This SOM applies when one of the following conditions is met:
   1. Multiple journals are registered in a consistency group of CCI.
   2. Multiple journals are registered in an extended consistency group.
   3. Journals are accumulated at the secondary site, causing the system performance to decrease.
2. If SOM 690 is set to ON and the Write Pending rate is 60% or higher, the journal copy is disabled regardless of the setting of this SOM.
3. When the host write speed is faster than the JNL copy speed, the usage rate of the master journal increases.
4. This SOM is effective within the range of each CLPR. Therefore, an operation target LPRxx (xx= 00 to 31) needs to be selected before setting this SOM to ON/OFF.

   For example, when setting this SOM only to CLPR0 (even though this SOM is not set to CLPR 1 to 31), select "LPR00" and then set this SOM to ON/OFF. If "System" is selected and then this SOM is set to ON, this SOM is not effective for any of the CLPRs.

5. Set SOM 1043 to ON when journals are not accumulated at the RCU. If journals have already been accumulated at the RCU, journal copy does not start until the journal usage rate becomes 0%. (If you need to set SOM 1043 to ON while journals are accumulated, set Purge Suspend, and then perform resync.)

Mode 1068 = ON (default): Drive response delay is checked and detected with conditions that are more severe than current conditions.

When SOM 144 is set to ON, the drive with response delay is blocked.

Target drive: HDD, FMD, SSD

Mode 1068 = OFF: Drive response delay is checked and detected with current conditions.

The behavior varies depending on the combinations of SOM settings. For details, contact customer support (see SOM144 sheet).

Notes:

1. Apply this mode to detect a minor delay in drive response.
2. When a delay is suspected, a processing to refer to the statistics data and determine the delay works.
3. If SOM 157 is set to ON, the output prevention status of SSB=A4CE is not cleared in one-day cycle.
4. When applying this mode only, a SIM for delay detection is reported but the drive is not blocked. To block the drive, SOM 144 also needs to be applied.

Mode 1069 = ON:

• Byte 3, Additional Length, is 32h regardless of the SOM 972 and SOM 973 settings.
• Byte 8-11, Page Size (number of blocks), is 0x1500 (42MB) regardless of the SOM 972 and SOM 973 settings.
• Byte 50-53, Optional Write Same Granularity (number of blocks), is 0x200 (256KB) when SOM 972 is ON regardless of the SOM 973 setting.
• Byte 50-53 is 0x10 (8KB) when SOM 972 is OFF and SOM 973 is ON.
• Byte 50-53 is 0x1500 (42MB) when both SOM 972 and SOM 973 are OFF.

Mode 1069 = OFF (default):

• Byte 3, Additional Length, is 2h regardless of the SOM 972 and SOM 973 settings.
• Byte 8-11, Page Size (number of blocks), is 0x200 (256KB) when SOM 972 is ON regardless of the SOM 973 setting.
• Byte 8-11 is 0x10 (8KB) when SOM 972 is OFF and SOM 973 is ON.
• Byte 8-11 is 0x1500 (42MB) when both SOM 972 and SOM 973 are OFF.
• Byte 50-53, Optional Write Same Granularity (number of blocks), is not applicable.

Notes:

1. This SOM is applied when the page problem occurs in an environment where Symantec ASL 6.0.5 or higher is used and SOM 972 and/or 973 is set to ON.
2. When this SOM is set to ON, reclamation processing is delayed.
3. The priority of setting when SOMs are set at the same time is SOM 1069, 972, and then 973. The setting of higher priority SOM is enabled.

Mode 1070 = ON: The status change of all pairs in a CTG is performed for 50 msec.

Mode 1070 = OFF (default): The status change of all pairs in a CTG is performed for 1 msec.

Notes:

1. This SOM is applied when reducing the time to complete status change of all pairs in a CTG at a group operation (suspension and resync operation) with the GAD CTG function. In a system configuration where host I/O performance is prioritized, do not use this SOM because setting this SOM may affect the host I/O performance.
2. The MP usage rate increases during status change of all pairs in a CTG. For details about approximate percentage increase in MP usage rate, contact customer support (see SOM1070 sheet).

Universal Volume Manager

Mode 1080 = ON: The time to run the reset command for the quorum disk on the external system is 15 seconds to eliminate the impacts on commands run for the other external devices that share the Target port with the quorum disk on the external system.

If a response to ABTS is delayed for 12 seconds or longer, the quorum disk may be blocked.

Mode 1080 = OFF (default): The time to run a reset command for the quorum disk when performance of a path degrades is 3 seconds so that a retry is performed by an alternate path to avoid quorum disk blockage.

Notes:

1. This SOM is applied if avoiding impacts on commands for other external devices that share a Target port on an external system side with a quorum disk is prioritized over preventing quorum disk blockage when a response to ABTS is delayed due to path performance degradation in a configuration where the Target port is shared between external devices and the quorum disk.
2. When connection performance degradation occurs, the quorum disk blockage is more likely to occur.

Universal Volume Manager

Mode 1083 = ON: DP-VOL deletion is enabled.

Mode 1083 = OFF (default): DP-VOL deletion is disabled.

Notes:

1. This SOM is applied when the following conditions are met.
   • A DP-VOL with data direct mapping attribute is deleted.
   • The data of external volume with data direct mapping attribute associated with a deletion target DP-VOL with data direct mapping attribute will not be used again.
2. When SOM 1083 is set to ON, the data of external volumes cannot be guaranteed.
3. When DP-VOL deletion is performed without disconnecting an external volume, the data of the external volume cannot be guaranteed.

Universal Volume Manager

Mode 1086 = ON (default): The performance improvement is enabled.

Mode 1086 = OFF: The performance improvement is disabled.

Notes:

1. This SOM is applied when the IOPS performance of an external storage system is higher than 80k × the number of installed MPBs, which is the value of IOPS that an entire local storage system sends to an external storage system.
2. When it is required to set this SOM to OFF, if IOPS sent from the local storage system to the external storage system is higher than 80k × the number of installed MPBs, reduce the IOPS to lower than 80k × the number of installed MPBs, and then set this SOM to OFF. (Otherwise CWP increases and cache is overloaded.)

Mode 1097 = ON (default): When SIM=452XXX, 462XXX, 3077XY, 4100XX, or 410100 is reported, the warning LED does not blink.

Mode 1097 = OFF: When SIM=452XXX, 462XXX, 3077XY, 4100XX, or 410100 is reported, the warning LED blinks.

Note: This SOM disables the warning LED to blink when specific SIMs are reported.

Dynamic Tiering

Mode 1106 = ON: The rebalance (the same as the rebalance that works at pool expansion or after 0 data page reclamation) (*3) works when one of the following conditions is met:

1. The usage rate is checked for parity groups in a pool once a day, and the usage rate is not balanced (*1) among parity groups.
2. After 0 data page reclamation, the number of reclaimed pages is 0 (*2).

Mode 1106 = OFF (default): The rebalance does not work even when the usage rate is not balanced.

*1: How to determine whether usage rate is unbalanced among parity groups

The pool usage rate is determined as unbalanced when there is 25% or more difference between the usage rate of each parity group in the pool and the average.

Note: For DT pools (including those with active flash attribute), the average of parity group usage rates is calculated per tier.

Examples:

1. In a DP pool, if the usage rates of PG1, PG2, and PG3 are 50%, 40%, and 30% respectively, it is not determined as unbalanced, because:
   • The average parity group usage rate is (50%＋40%＋30%) / 3 ＝40%.
   • The difference in usage rate between each parity group and the average is 10% at the maximum.
2. In a DP pool, if the usage rates of PG1, PG2, and PG3 are 80%, 40%, and 30% respectively, it is determined as unbalanced because:
   • The average parity group usage rate is (80%＋40%＋30%) / 3 ＝50%.
   • The difference in the usage rate between each parity group and the average is 30% at the maximum.
3. In a DT pool, if the usage rates of PG1, PG2, and PG3 are 80% (SSD), 40% (SAS15K) and 30% (SAS15K), it is not determined as unbalanced, because:
   • The average parity group usage rate of Tier1 is (80%) / 1 ＝80% and the difference in the usage rate between the parity group and the average is 0%.
   • The average parity group usage rate of Tier2 is (40%＋30%) / 2 ＝35% and the difference in the usage rate between the parity group and the average is 5% at the maximum.

*2: Condition for rebalance after 0 data page reclamation

When the mode is set to ON, rebalance works even when reclaimed page is 0 at 0 data page reclamation.

Notes:

1. The mode is applied when balancing the usage rate is required at a customer site where the usage rate is not even.
2. The term "page usage rate" refers to the percentage of the number of assigned pages in each PG compared to the total number of pages in the pool.

   In the case of a DT pool, the term "total number of pages" is the number of pages assigned within each specific tier.

Mode 1113 = ON: The processing other than garbage collection and de-staging among the asynchronous processing for host I/Os of the capacity saving function is stopped.

Note: While the capacity reduction processing is not working, the capacity saving rate might degrade.

Mode 1113 = OFF (default): The capacity saving function fully works.

Notes:

1. This SOM is applied when a failure occurs due to the asynchronous processing of the capacity saving function so that identifying a failure part, reducing the MP usage rate, and preventing the problem from further expanding are required.
2. When this mode is set to ON, the capacity reduction processing does not work and the capacity saving rate degrades.
3. SOM 1113 is related to SOM 1112. When both modes are set to ON, the setting of SOM 1112 is prioritized over that of SOM 1113.

   Behavior when SOM 1112 is set to ON:

   All of asynchronous processing for host I/Os among those processing related to the capacity saving function are stopped, which means that the garbage collection and de-staging do not work, so that write I/Os to DP volumes with Compression or Deduplication and Compression set are disabled.

Mode 1118 = ON: When a failure occurs in the Expander chip mounted on a controller board (CTLS, CTLSE) or an ENC board, the reuse function does not work but SIM=CF12XX is reported and the ENC is blocked.

Mode 1118 = OFF (default): When a failure occurs in the Expander chip mounted on a controller board (CTLS, CTLSE) or an ENC board, the reuse function works.

If the ENC is reusable, SIM=CF12XX and then CF14XX are reported, and the ENC is reused.

If the ENC is not reusable, SIM=CF12XX is reported, and the ENC is blocked.

Note: The ENC reuse function is enabled as default. This SOM is applied when you need to disable the ENC reuse function.

Mode 1169 = ON (default when using CTO automation tool): Deduplication processing is not performed during resync processing. (*1)

Mode 1169 = OFF (default when not using CTO automation tool): Deduplication processing is performed during resync processing.

*1: To reduce the capacity consumption in the case that the pool capacity is almost depleted for example, the deduplication processing might be performed during the resync processing. In particular, the following cases apply:

• The usage rate exceeds the warning threshold.
• Free capacity is smaller than about 240 GB.

Notes:

1. When SOM 1280 is ON, deduplication processing is performed even when SOM 1169 is ON.
2. If conditions to disable deduplication processing by SOM 1191 are met, deduplication processing is not performed even when SOM 1169 is OFF. For details about the conditions to disable deduplication processing, contact customer support (see SOM1191 sheet).
3. When SOM 1169 is set to ON, like the post-processing mode, estimating and reserving the capacity of a temporary storing area in the copy target DP volume or pool in advance is necessary.
4. SOM 1169 is not effective for the initial copy at pair creation, but there are some exceptions for SI and VM, such as pair creation using a used volume for S-VOL. In this case, deduplication processing is performed or not performed according to the mode setting.
5. SOM 1169 is not related to determining whether to perform deduplication processing in synchronization with initial write. For example, the setting of SOM 1169 does not contribute to a reduction in time to migrate data to a newly defined volume.

Mode 1174 = ON: A path logged in from a host or an external storage system is excluded from the WWN discovery target.

Mode 1174 = OFF (default):A path logged in from a host or external storage system is included in the WWN discovery target.

Notes:

1. Apply SOM 1174 when discovery is performed while specifying a universal port that is being logged in from a host or an external storage system.
2. When SOM 1174 is set to ON, external volumes cannot be created using the paths being logged in from hosts and external storage systems.
3. When WWN discovery is performed while SOM 1174 is set to ON, the storage system being logged in from hosts and external storage systems are displayed as [Unknown] in the discovery result.

   Discovery works at the following operations or commands:

   • Device Manager - Storage Navigator: External volume addition, external path setting change
   • CCI: raidcom add external_grp, raidcom add path, raidcom discover external_storage, raidcom discover lun
4. By specifying the -safety_check enable option for the above CCI commands, path disconnection can be prevented same as in the case of setting the mode to ON. The option is supported with the following versions. For details, see the Command Control Interface Command Reference.

   DKCMAIN: 93-04-01-x0/00 and later

   CCI: 01-61-03/xx and later

Mode 1191 = ON: The inline deduplication processing is disabled when the average of MP usages on the entire storage system is 50% or higher, or CPW is 30% or higher. For details, contact customer support (see SOM1191 sheet).

Mode 1191 = OFF (default): Regardless of MP usage and CWP rate, the inline deduplication processing is not disabled.

Notes:

1. This SOM is applied when reducing impact on I/O performance is required at online data migration for a virtual volume with capacity saving enabled and the inline mode set.
2. If the mode is set to ON, the frequency of the asynchronous deduplication processing increases after storing the data in a temporary area so that the pool capacity decreases due to consumption of the temporary area. To use the mode therefore, decrease in pool capacity must be acceptable. In particular, verify the capacity of the temporary area in the pool by using the following conditional expressions.

   <Setting the mode at data migration>

   Pool capacity × depletion threshold (%) / 100 is larger than current used pool capacity + (amount of data to be migrated × (100 – estimated compression ratio (%)(*))/ 100)

   <Setting the mode during normal operation>

   Pool capacity × depletion threshold (%) / 100 is larger than current used pool capacity + (amount of data to be written to area without having been written × (100 – estimated compression ratio (%)(*)) / 100)

   * Estimated compression ratios is the ratio of the estimated compression reduction effect. To convert the compression ratio in N:1 format to percentage, use the formula. Compression ratio (%) = (1 – 1 / N) × 100

   If the estimated compression ratio is unknown, use 0% as the estimated compression ratio.

3. To set the mode to ON, first estimate temporary area in a pool and then reserve it in advance.
4. By setting the mode to ON, the inline deduplication processing is disabled when the average MP usage is 50% or higher even though SOM 1280 is set to ON.
5. When SOM 1169 is set to ON, the inline deduplication at copy processing is disabled regardless of SOM 1191 setting.
6. For conditions to stop deduplication processing according to the setting combination of SOM 1191, SOM 1247, and SOM 1248, contact customer support (see SOM1191 sheet).

Universal Replicator

Global-active device

* The behavior when the mode is ON or OFF differs from that when user SOM 5 or SOM 6 is set to ON or OFF.

Mode 1198 = ON: The behavior varies depending on the setting combination of SOM 1198 and SOM 1199. For details, contact customer support (see SOM1198_1199 sheet).

Mode 1198 = OFF (default): The behavior varies depending on the setting combination of SOM1198 and SOM1199. For details, contact customer support (see SOM1198_1199 sheet).

Notes:

1. This SOM is applied to enable users who do not have SVP and use CCI in TC, UR, or GAD operations to perform capacity expansion for volumes with 4TB or less used in TC, UR, or GAD pairs.
2. Setting the modes affects the I/O response performance depending on the I/O pattern.
3. Setting the modes affects the initial copy time depending on the conditions.

Universal Replicator

Global-active device

At TC, UR, or GAD pair creation or resync operation, the difference management method is switched from hierarchy difference management to SM difference management.

* The behavior when the mode is ON or OFF differs from that when user SOM 5 or SOM 6 is set to ON or OFF.

Mode 1199 = ON: The behavior varies depending on the setting combination of SOM 1198 and SOM 1199. For details, contact customer support (see SOM1198_1199 sheet).

Mode 1199 = OFF (default): The behavior varies depending on the setting combination of SOM 1198 and SOM 1199. For details, contact customer support, see the SOM1198_1199 sheet.

Notes:

1. This SOM is applied to enable users who do not have SVP and use CCI in TC, UR, or GAD operations to switch difference management method from hierarchy difference management to SM difference management for volumes of 4TB or less used in TC/UR/GAD pairs.
2. Setting the modes affects the I/O response performance depending on the I/O pattern.
3. Setting the modes affects the initial copy time depending on the conditions.

Mode 1202 = ON:

• Synchronous read I/Os are disabled.
• Read I/Os other than synchronous read are disabled.
• Write I/Os are disabled.

Mode 1202 = OFF (default):

• Synchronous read I/Os can be done by collection read.
• Read I/Os other than synchronous read are disabled.
• Write: I/Os are disabled.

Notes:

1. Apply this mode when changing the behavior back to the previous one is required during FMD and SSD firmware replacement.
2. When this mode is set to ON, the host I/O performance during FMD or SSD drive firmware replacement may be degraded.

Dynamic Provisioning

Dynamic Tiering

Thin Image

Mode 1204 = ON: When the MP usage rate is within the range 30 to 50%, the processing interval is shortened to improve the page migration throughput.

Mode 1204 = OFF (default): There is no change for the processing interval.

For details, (see sheet SOM 1204).

Notes:

1. This SOM is applied when the following conditions are met:
   • The MP usage rate constantly exceeds 30%.
   • Prioritizing the page migration processing over the I/O processing is required.
2. When SOM 1204 is set to ON, the operation frequency of the relocation processing increases so that the host I/O response performance is degraded.
3. When SOM 904 is set to ON, the SOM 904 setting is prioritized.
4. By setting SOM 1204 to ON, the MP usage rate increases by 3 to 10% due to the asynchronous processing, and the host I/O response may be degraded.

Dynamic Provisioning

Dynamic Tiering

Thin Image

Mode 1205 = ON: Background unmap runs at up to 42 MB/s.

Mode 1205 = OFF (default): Background unmap runs at up to 10 GB/s.

Notes:

1. The mode is applied to prevent the host response performance from being degraded due to background unmap.
2. When SOM 1122 is set to ON, the SOM 1122 setting is prioritized.
3. As releasing physical areas runs at the normal speed, the following phenomena may occur, though the phenomena are solved immediately after the physical area release is complete:
   • The used pool capacity does not decrease immediately after DP volume deletion.
   • The saving ratio seems to be lower temporarily.
   • The used pool capacity may increase due to rebalance.

Universal Replicator

Journal data copy is disabled when the following conditions (1) and (2), or (1) and (3) are met:

1. 4096 or more journal data sets are accumulated on RCU.
2. The write pending rate of a journal volume in an MPB that has the ownership of the journal on RCU exceeds the threshold, 25% (mode OFF) or 50% (mode ON). (Including the write pending rate of those other than the journal volume)
3. On RCU, it takes 15 seconds or longer to start a restore operation after the copy processing of journals is complete.

Note: Even when the above conditions are met, if the time stamp of accumulated journal datasets is the same in a configuration where multiple journals are added to a consistency group, journal data copy is not disabled.

Mode 1211 = ON: The threshold for the write pending rate is 50%.

Mode 1211 = OFF (default): The threshold for the write pending rate is 25%.

Notes:

1. Apply this mode when any of the following conditions is met:
   • Disabling journal data copy is enabled by meeting one of the following conditions:

     SOM 1043 is set to ON for each CLPR on the secondary site.

     A configuration where multiple journals are added to a CCI consistency group.

2. If the host write I/O speed is faster than the journal data copy speed, the usage of the master journal increases.
3. Though this SOM can work on UR RCU, apply it to both MCU and RCU assuming a Disaster Recovery operation.
4. This mode is related to SOM 1043.
5. If SOM 690 is set to ON and the write pending rate is 60% or higher, journal data copy is disabled regardless of the setting of this mode.
6. This SOM is effective per CLPR. Therefore, select a target LPR xx (xx= 00 to 31), and then set the mode to ON or OFF. For example, when setting the mode to CLPR0 (even though CLPR 1 to 31 are not defined), select LPR00, and then set the mode to ON or OFF. If you just select System and then set the mode, the mode cannot be enabled for any CLPRs.

Mode 1223 = ON: The mapping consistency check processing does not run.

Mode 1223 = OFF (default): The mapping consistency check processing runs.

Note: Apply this SOM when all the following conditions are met:

1. The microcode that supports the mode is applied (93-04-01 and later).
2. The response time of Write Same command increases about 0.1 msec.
3. The length of Write Same command is short (less than 256KiB).

Thin Image

Volume Migration

Universal Replicator

Mode 1224 = ON: Ownership migration at program product pair deletion is disabled.

Mode 1225 = OFF (default): Ownership migration at program product pair deletion is performed.

* Different from other program products, the ownership in an MPU with the journal group ownership is migrated as follows in a UR configuration:

• Ownership migration target: LDEV (journal volume, remote CMDDEV).
• Timing when ownership migration takes place: Journal volume deletion, journal group deletion from EXCTG, and mirror allocation release.

Notes:

1. Apply the mode when preventing the MP usage rate increase is required.
2. Ownerships are in a specific MPU so that I/Os may be concentrated on the MPU.
3. Ownership migration does not work at pair deletion.

Mode 1251 = ON: When an error caused by an I-path failure is detected during controller recovery, the recovery is continued. In addition, some MPs of the other controller are forcibly blocked.

Mode 1251 = OFF (default): When an error caused by an I-path failure is detected during controller recovery, the recovery is stopped.

Notes:

1. Apply the mode when controller recovery fails due to an I-path failure (SSB=3560), and the controller recovery still fails for the same reason even when the controller has been replaced with a new part.
2. The MP usage rate increases because half of MPs on the controller are blocked.
3. An error may be returned temporarily to the host because of the MP blockage.
4. When controller recovery is performed while the mode is set to ON, MPs on the other controller are blocked due to failure.

Volume Migration

Thin Image

TrueCopy

Global-active device

Universal Replicator

* Replication program products: SI, VM, Thin Image, TC, GAD, UR.

Mode 1254 = ON: The copy processing running in the background* stops when the WP rate of the copy target CLPR is 35% or higher.

Mode 1254 = OFF (default):

• SI, VM, TI: As per the SOM 467 setting.
• TC, GAD: As per the SOM 689 setting.
• UR: As per the SOM 690 setting.

* The copy processing running in the background refers to the following processing:

• SI: Pair initial copy, pair initial copy (Steady Split), pair initial copy (Quick Split), Steady Split, Quick Split (it does not stop for a pair whose synchronization rate is 100%), Normal Resync (it does not stop for a pair whose synchronization rate is 100%), Reverse Copy (it does not stop for a pair whose synchronization rate is 100%), background copy.
• VM: Pair initial copy.
• TI: Copy processing by restore, copy processing by clone.
• TC: Copy running in background, initial copy, pair creation, resync, swap resync, horctakeover (swap resync run during horctakeover).
• GAD: Initial copy, pair creation, resync, swap resync, horctakeover (swap resync run during horctakeover).
• UR: Copy or restore running in background, initial copy, update copy, journal copy (initial and update copy), journal restore, issuing read-journal command to primary storage system, data copy from master journal to restore journal, copying restore journal data for secondary volume, pair creation, resync, swap resync, delta resync, horctakeover (swap resync run during horctakeover).

Notes:

1. Apply this mode when all the following conditions are met:
   1. Preventing the performance of a host write I/O to a DRD-VOL from being degraded due to overload by the copy processing running in the background is required.
   2. It is acceptable that completing the copy processing running in the background for a volume (*1) belonging to a CLPR whose WP rate is 35% or higher takes extra time equal to the time period during which the WP rate of the copy target CLPR is 35% or higher.
   3. Setting the mode per CLPR is required. (Setting for all CLPRs, use SOM 1254.)
   4. A The mode setting for a CLPR of UR S-VOL, and that for a CLPR of a journal volume are the same. (The mode is set to ON or OFF for both CLPRs.)

   *1: Note that in CLPRs with the mode set to ON, the copy processing does not make progress for not only a DRD-VOL but also a normal volume and a virtual volume with capacity saving disabled.

2. By setting the mode to ON, the copy processing running in the background is stopped when the WP rate is 35% or higher regardless of the settings of SOM 467, SOM 689, and SOM 690.
3. Completing the copy processing running in the background for a volume (*2) belonging to a CLPR whose WP rate is 35% or higher takes extra time equal to the time period during which the WP rate of the copy target CLPR is 35%.

   SOM 1260 cannot be applied if the copy processing, such as the case of data migration or volume migration, must be completed in a certain time period.

   Recovering a pair that is suspended due to failure takes longer time too.

   *2: Note that in CLPRs with the mode set to ON, the copy processing does not make progress for not only a DRD-VOL but also normal volume and virtual volume with capacity saving disabled.

   *4: Note that in CLPRs with the mode set to ON, the copy processing does not make progress for not only a DRD-VOL but also normal volume and virtual volume with capacity saving disabled.

4. When UR is used, if 35% or higher WP rate continues for a long time on RCU, a journal volume becomes full and may be suspended on MCU.

   To disable the copy running in the background of replication program products other than UR, use different CLPRs for the UR S-VOL and the journal volume, and for the DRD-VOL for which preventing performance degradation is required on RCU, and set the mode to ON for the CLPR of the DRD-VOL only.

5. In a 3DC configuration, if 35% or higher WP rate continues for a long time on the second RCU, a journal volume becomes full and may be suspended on MCU and the first RCU. In this case, even if you perform delta resync, all data copy from P-VOL to S-VOL works same as the case when delta resync fails.
6. In a UR M:N open CTG configuration, even if there is one storage system where the WP rate reaches 35% or higher on RCU, copy processing will be stopped on all storage systems in this configuration, including the storage systems with SOM 1260 disabled.
7. When UR is used, if operations are switched to RCU, as the previous MCU becomes RCU, meet the following conditions:
   1. The SOM setting is same for MCU and RCU.
   2. If different CLPRs are used for the UR S-VOL and the journal volume, and for a DRD-VOL for which preventing performance degradation is required on RCU, use different CLPRs for the UR S-VOL and the journal volume, and for a DRD-VOL for which preventing performance degradation is required on MCU too.
8. In a 3DC configuration, because operations on MCU can be switched to the first RCU or the second RCU, make sure the SOM setting is the same on the MCU, the first RCU and the second RCU.

ShadowImage

Volume Migration

TrueCopy

Global-active device

Universal Replicator

*: SI, VM), Thin Image, TC, GAD, UR.

Mode 1260 = ON:

SI, VM, TI, TC, GAD, UR: The copy processing running in the background* stops when the WP rate of the copy target CLPR is 35% or higher.

Mode 1260 = OFF (default):

SI, VM, TI: As per the SOM 467 setting.

TC, GAD: As per the SOM 689 setting.

UR: As per the SOM 690 setting.

* The copy processing running in the background refers to the following processing:

• SI: Pair initial copy, pair initial copy (Steady Split), pair initial copy (Quick Split), Steady Split, Quick Split (it does not stop for a pair whose synchronization rate is 100%), Normal Resync (it does not stop for a pair whose synchronization rate is 100%), Reverse Copy (it does not stop for a pair whose synchronization rate is 100%), background copy.
• VM: Pair initial copy.
• TI: Copy processing by restore, copy processing by clone.
• TC: Copy running in background, initial copy, pair creation, resync, swap resync, horctakeover (swap resync run during horctakeover).
• GAD: Initial copy, pair creation, resync, swap resync, horctakeover (swap resync run during horctakeover).
• UR: Copy or restore running in background, initial copy, update copy, journal copy (initial and update copy), journal restore, issuing read-journal command to primary storage system, data copy from master journal to restore journal, copying restore journal data for secondary volume, pair creation, resync, swap resync, delta resync, horctakeover (swap resync run during horctakeover).

Notes:

1. Apply the mode when all the following conditions are met:
   1. Preventing the performance of a host write I/O to a DRD-VOL from being degraded due to overload by the background copy processing is required.
   2. It is acceptable that completing the background copy for a volume (*1) belonging to a CLPR whose WP rate is 35% or higher takes extra time equal to the time period during which the WP rate of the copy target CLPR is 35% or higher.
   3. Setting the mode per CLPR is required. (Setting for all CLPRs, use SOM 1254.)
   4. The mode setting for a CLPR of UR S/VOL, and that for a CLPR of a journal volume are the same. (The mode is set to ON or OFF for both CLPRs.)

   *1: Note that in CLPRs with the mode set to ON, the copy processing does not make progress for not only a DRD-VOL but also a normal volume and a virtual volume with capacity saving disabled.

2. By setting the mode to ON, the copy processing running in the background is stopped when the WP rate is 35% or higher regardless of the settings of SOM 467, SOM 689, and SOM 690.
3. Completing the copy processing running in the background for a volume (*2) belonging to a CLPR whose WP rate is 35% or higher takes extra time equal to the time period during which the WP rate of the copy target CLPR is 35%.

   SOM 1260 cannot be applied if the copy processing, such as the case of data migration or volume migration, must be completed in a certain time period.

   Recovering a pair that is suspended due to failure takes longer time too.

   *2: Note that in CLPRs with the mode set to ON, the copy processing does not make progress for not only a DRD-VOL but also normal volume and virtual volume with capacity saving disabled.

4. When UR is used, if 35% or higher WP rate continues for a long time on RCU, a journal volume becomes full and may be suspended on MCU.

   To disable the copy running in the background of replication program products other than UR, use different CLPRs for the UR S-VOL and the journal volume, and for the DRD-VOL for which preventing performance degradation is required on RCU, and set the mode to ON for the CLPR of the DRD-VOL only.

5. In a 3DC configuration, if 35% or higher WP rate continues for a long time on the second RCU, a journal volume becomes full and may be suspended on MCU and the first RCU. In this case, even if you perform delta resync, all data copy from P-VOL to S-VOL works same as the case when delta resync fails.
6. In a UR M:N open CTG configuration, even if there is one storage system where the WP rate reaches 35% or higher on RCU, copy processing will be stopped on all storage systems in this configuration, including the storage systems with SOM 1260 disabled.
7. When UR is used, if operations are switched to RCU, as the previous MCU becomes RCU, meet the following conditions:
   1. The SOM setting is same for MCU and RCU.
   2. If different CLPRs are used for the UR S-VOL and the journal volume, and for a DRD-VOL for which preventing performance degradation is required on RCU, use different CLPRs for the UR S-VOL and the journal volume, and for a DRD-VOL for which preventing performance degradation is required on MCU too.
8. In a 3DC configuration, because operations on MCU can be switched to the first RCU or the second RCU, make sure the SOM setting is the same on the MCU, the first RCU and the second RCU.

Dedupe and Compression

Mode 1267 = ON: The asynchronous processing of capacity saving listed below runs at low speed.

Mode 1267 = OFF (default): The asynchronous processing of capacity saving listed below runs at normal speed.

Asynchronous processing that runs at low speed by setting the mode to ON

• Disabling of the capacity saving function
• Deletion of LDEVs for which the capacity saving function is enabled
• Garbage collection
• Asynchronous capacity reduction processing
• Compression conversion of compression accelerator
• Garbage collection for collecting unnecessary meta data or user data of deduplication system data volume (data store)
• Deletion of unnecessary hash data for deduplication
• Expansion of metadata area of the capacity saving
• Correction of control information when SOM 1208 is set to ON
• Health check when SOM 1237 is set to ON

Notes:

1. Apply this mode in the following cases:
   1. There is a possibility of drive overload by the asynchronous processing (asynchronous capacity reduction, disabling capacity saving, compression conversion of compression accelerator) that works after the data reduction setting (capacity saving, compression accelerator) is changed.
   2. The drive is overloaded by asynchronous processing of capacity saving.
2. By setting the mode to ON, the capacity saving ratio may decrease.
3. When an adaptive data reduction setting change is complete after setting the mode to ON, set the mode to OFF.