System option modes (SOMs)

15

Common

This SOM can reduce the host response time to be within about 6 seconds.

Notes:

1. This SOM is used on a storage system where slow or delayed drive response 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 (interaction with other SOMs, operational details), contact customer support (see SOM015 sheet).

ON

-

22

Common

Regarding the correction copy or the drive copy, in case ECCs/LRC PINs are set on the track of copy source HDD, SOM 22 can be used to interrupt the copy processing (default) or to create ECCs/LRC PINs on the track of copy target HDD to continue the processing.

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: 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.

OFF

None

142

Common

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. When this SOM is set 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 the half of the normal threshold.

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

*The default setting for this SOM depends on the microcode level:

• Default = ON: 83-03-28 and later (within 83-03-2x range), 83-04-03 and later
• Default = OFF: earlier than 83-03-28, earlier than 83-04-03 (within 83-04-0x range)

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. This SOM is effective for the entire storage system.

ON

-

144

Common

This mode is intended to detect and block an HDD whose response is permanently delayed to keep reliability.

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: 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 SOM1068 to ON or OFF, detects a drive response delay, the drive with response delay is blocked.

   SOM144 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 and A4DD are logged, the drive with response delay is blocked, and then 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 sheet SOM144).

   Mode 144 = OFF: 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.

ON (88-01-02 only)

OFF (88-01-03 and later)

-

310

Common

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.

OFF

-

448

Universal Replicator

When the SVP detects a blocked path:

Mode 448 = ON: An error is assumed and the mirror is immediately suspended.

Mode 448 = OFF (default): If the path does not recover within a specified period of time, an error is assumed and the mirror is suspended.

Note: SOM 448 setting is available only when SOM 449 is set to OFF.

OFF

-

449

Universal Replicator

This SOM is used to enable and disable detection of communication failures between the MCU and RCU.

Mode 449 = ON (default): On the MCU side, checking read journal disruption from RCU is disabled, and monitoring read journal failures is disabled on the RCU side.

Mode 449 = OFF: Detecting communication failures between the MCU and RCU is enabled.

Notes:

1. This SOM applies 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, recover it in accordance with the procedure in Recovery from UR Failure in TROUBLE SHOOTING section of Maintenance Manual.

ON

MCU

454

Virtual Partition Manager

CLPR (function of Virtual Partition Manager) partitions the cache memory in the storage system into multiple virtual cache and assigns the partitioned virtual cache for each use. If a large amount of cache is required for a specific use, it can minimize the impact on other uses. The CLPR function works as follows depending on whether SOM 454 is set to ON or OFF.

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.

OFF

-

457

Universal Volume Manager

High-speed LDEV format for external volumes.

Mode 457 = ON: The high-speed LDEV format for external volumes is available by SOM 457 to ON. When SOM 457 is ON, if you select an external volume group and perform an LDEV format, any write processing on the external logical units will be skipped.

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.

OFF

Both

459

ShadowImage

When the S-VOL of an SI/SIz pair is an external volume, the transaction to change the status from SP-PEND to SPLIT is as follows:

Mode 459 = ON (default): When suspending an SI pair: Waits for the copy data in cache memory to completely destage to the external volume S-VOL before changing the pair status to SUSPEND.

Mode 459 = OFF (default): When suspending an SI pair: The status changes to SUSPEND as soon as all of the delta data is copied to S-VOL cache. The status does not wait for cache to destage to the S-VOL external volume.

OFF

ON

-

467

ShadowImage

Snapshot

Universal Volume Manager

Volume Migration

For the following features, the current copy processing slows down when the percentage of “dirty” data is 60% or higher, and it stops when the percentage is 75% or higher. Mode 467 is provided to prevent the percentage from exceeding 60%, so that the host performance is not affected.

• SI
• Snapshot
• UVM
• Volume Migration

Mode 467 = ON (default): Copy overload prevention. Copy processing stops when the percentage of “dirty” data reaches 60% or higher. When the percentage falls below 60%, copy processing restarts.

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

Caution: This SOM must always be set to ON when using an external volume as the secondary volume of any of the applicable replication products.

Notes:

1. It takes longer to finish the copy processing because it stops for prioritizing the host I/O performance.
2. 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.
3. Check the write pending rate of each CLPR per MP blade. Even though there is some free cache capacity in the entire system, if the write pending rate of an MP blade to which pairs* belong exceeds the threshold, the copy operation is stopped.

   *Applies to pairs of SI, SIz, FCv2, FCSE, Snapshot, and Volume Migration.

ON

-

506

Universal Replicator

This SOM is used to enable Delta Resync with no host update I/O by copying only differential JNL instead of copying all data.

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.

ON

Both

589

Universal Volume Manager

When this SOM is ON, the frequency of progress update of disconnection is changed.

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%).

OFF

Both

689

TrueCopy

global-active device

Allows you to slow the initial copy and resync operations when the write-pending rate on the RCU exceeds 60%.

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. Do not set this SOM if the primary or secondary system is connected to USP V/VM with microcode earlier than 60-02-xx. If this SOM is applied and the write-pending rate reaches 60%, pair suspend might occur.

OFF

Both

690

Universal Replicator

This SOM is used to prevent Read JNL or JNL Restore when the Write Pending rate on RCU exceeds 60% as follows:

• 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.
5. When USP/NSC is used on the P-VOL side, this SOM cannot be used. If this SOM is set to ON, SSB=8E08 on the P-VOL side and SSB=C8D1 on the S-VOL side might be output frequently.

OFF

RCU

701

Universal Volume Manager

Issues the Read command at the logical unit discovery operation using UVM.

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 the external storage is USP/NSC and the Open LDEV Guard attribute (VMA) is defined on an external device, set this SOM to ON.
2. When this SOM is set to ON, it takes longer time to complete the LU discovery. The amount of time depends on external storages.
3. With this SOM OFF, if searching for external devices with VMA is set, the VMA information cannot be read.
4. 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
5. As the VMA information is USP/NSC specific, this SOM does not need to be ON when the external storage is other than USP/NSC.
6. Set this SOM to OFF when an external volume to which nondisruptive migration (NDM) attribute is set exists.

OFF

-

704

ShadowImage

Volume Migration

To reduce the chance of MIH, this SOM can reduce the priority of ShadowImage, Volume Migration, or Resync copy internal IO requests so that host IO has a higher priority. This SOM creates new work queues where these jobs can be assigned with a lower priority.

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.

OFF

-

721

Common

When a parity group is uninstalled or installed, the following operation is performed according to the setting of SOM 721.

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.

OFF

-

725

Universal Volume Manager

This SOM determines the action that will be taken when the status of an external volume is Not Ready.

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.

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 prohibited when USP V/VM is used as an external storage system and its external volume is DP-VOL.
2. Applying this SOM is recommended when the above condition (1) is not met and SUN storage is used as an external storage.
3. Applying this SOM is recommended when the above condition (1) is not met and EMC CX series or Fujitsu Fibre CAT CX series is used as an external storage.
4. Applying this SOM is recommended if the above condition (1) is not met and 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.
5. While USP V/VM is used as an external storage system and its volume is DP-VOL, if some Pool-VOLs constituting the DP-VOL are blocked, external path blockade and recovery occurs repeatedly.
6. When a virtual volume mapped by UVM is set to pool-VOL and used as DP-VOL in local storage system, this SOM can be applied without problem.

OFF

-

734

Dynamic Provisioning

OFF

ON

-

741

Dynamic Provisioning

This SOM enables to switch over whether to report the following SIM for users to the service personnel:

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.

OFF

-

745

Universal Volume Manager

Enables to change the area where the information is obtained as the Characteristic1 item from SYMMETRIX.

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.

OFF

-

749

Dynamic Provisioning

Dynamic Tiering

Thin Image

This SOM disables the HDP Rebalance function and the HDT Tier relocation function which allow the drives of all ECC Groups in the pool to share the load.

Mode 749 = ON: The HDP Rebalance function and the HDT Tier relocation function are disabled.

Mode 749 = OFF (default): The HDP Rebalance function and the HDT 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.

OFF

-

757

Common

Enables/disables output of in-band audit logs.

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.

OFF

-

784

TrueCopy

Global-active device

This SOM can reduce the MIH watch time of RI/O for a TC or GAD pair internally so that update I/Os can continue by using an alternate path without MIH or time-out occurrence in the environment where Mainframe host MIH is set to 15 seconds, or Open host time-out time is short (15 seconds or less). This SOM is effective at initial pair creation or Resync operation for TC or GAD. (Not effective by just setting this SOM to ON.)

This SOM is applied to TC and GAD. This SOM supports Fibre remote copy paths but not 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 Mainframe host MIH time is set to 15 seconds.
2. This SOM is applied to the environment where OPEN host time-out time is set to 15 seconds or less.
3. This SOM is applied to reduce RI/O MIH time to 5 seconds.
4. 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.
5. 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.
6. If a failure occurs on the switched path between storage systems, Mainframe host MIH or Open server time-out may occur.
7. 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.
8. 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.
9. 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.
10. Operation commands are not available for promptly switching to an alternate path.
11. This SOM works for the pair for which initial pair creation or Resync operation is executed.
12. Micro-program downgrade to an unsupported version cannot be executed unless all the TC and GAD pairs are suspended or deleted.
13. For operational specifications in each combination of MCU and RCU of TC, contact customer support (see SOM784 sheet).
14. For GAD pairs, this SOM is effective if the microcode version supports GAD.
15. 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.

OFF

Both

855

ShadowImage

Volume Migration

By switching this SOM to ON/OFF when ShadowImage is used with SOM 467 set to ON, copy processing is continued or stopped as follows.

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 blade 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.

OFF

-

896

Dynamic Provisioning

Dynamic Tiering

Thin Image

This SOM enables or disables the background format function performed on an unformatted area of a DP/DT/TI pool.

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 a customer requires the background format for a DP/DT/TI pool in the environment where new page allocation (in the case that system files are created from a host for newly created multiple DP-VOLs, for example) frequently occurs and the write performance degrades because of an increase in write pending rate.
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.
5. The background format for FMC drives is not disabled. When FMC drives are used, use SOM 1093.

OFF

-

901

Dynamic Tiering

By setting this SOM to ON or OFF, the page allocation method of Tier Level ALL when the drive type of tier1 is SSD changes as follows.

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).

OFF

-

904

Dynamic Tiering

By setting this SOM to ON or OFF, the number of pages to be migrated per unit time at tier relocation is changed.

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.

OFF

-

908

Universal Replicator

This SOM can change CM capacity allocated to MPBs with different workloads.

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) A CLPR only for UR JNLG.

   (b) A configuration where MPBs and CLPRs are separately used for Open and Mainframe systems.

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.

OFF

Both

937

Dynamic Provisioning

Dynamic Tiering

By setting this SOM to ON, HDT monitoring data is collected even if the pool is a DP pool.

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.

OFF

-

1015

Universal Replicator

When a delta resync is performed in a 3DC multi-target configuration with TC and UR, this SOM is used to change the pair status to PAIR/Duplex directly and then complete the delta resync. If the delta resync fails and all differential data items are copied, the pair status changes to COPY/Pending regardless of the SOM 1015 setting, and then it changes to PAIR/Duplex.

When the existing delta resync function is required (pair status changes to COPY/Pending and then to PAIR/Duplex), set this SOM to ON before performing delta resync. If SOM 1015 is set (ON or OFF) while delta resync is being peformed, the setting is not applied.

Mode 1015 = ON: The pair status changes to COPY/Pending and then to PAIR/Duplex when a delta resync is performed in a 3DC multi-target configuration.

Mode 1015 = OFF (default): The pair status changes directly to PAIR/Duplex when a delta resync is performed in a 3DC multi-target configuration.

Notes:

1. The pair status changes directly to PAIR/Duplex when this SOM is OFF (default). Set this SOM to ON only when the status change to COPY/Pending and then PAIR/Duplex is required.
2. Set this SOM on the site of TC S-VOL in TC-UR 3DC configuration. If site switch by delta resync might occur, set this SOM on both TC primary and secondary sites.
3. For microcode versions and storage system models that do not support this SOM, even if this SOM is set to OFF on L site of TC-UR delta configuration, the behavior does not change but the status changes to COPY/Pending and then the delta resync is completed.
4. Regardless of the remote command device setting, the copy status does not change to COPY/Pending and then the delta resync is completed.
5. If a delta resync fails, all-data copy works. In this case, the pair status changes to COPY/Pending and then the delta resync is completed even when this SOM is set to OFF.
6. When this SOM setting is default (OFF), a delta resync operation is completed without pair status change to COPY/Pending. Therefore, if an operation depends on the pair status changing to COPY/Pending, such as running the CCI pairevtwait command, set this SOM to ON.
7. When this SOM setting is default (OFF) (pair status changes directly to PAIR/Duplex), SIMs and SSBs that are reported due to a pair status change to COPY/Pending are not reported.
8. If this SOM is set to ON or OFF during delta resync, the setting is not applied. Change this SOM setting before delta resync.
9. During delta resync, downgrading the microcode to a version that does not support this SOM 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.

OFF

MCU

1021

Universal Volume Manager

This SOM can enable or disable the auto-recovery for external volumes of an EMC storage system.

Mode 0121 = 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.

OFF

-

1043

Universal Replicator

This SOM disables journal copy.

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

For VSP Fx00 models and VSP Gx00 models, 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 MP blade/unit for which journal ownership at the RCU is defined is 25% or higher (including the write pending rate for other than journal volumes).
3. The initiator operating rate of the MP blade/unit for which journal ownership at the RCU is defined is 40% or higher.

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.)

OFF

Both

1067

Universal Replicator

This SOM is used to enable microcode downgrade to a version that does not support URxUR (including delta).

Mode 1067 = ON: Even when a UR pair has been registered, downgrading the microcode to a version that does not support URxUR (including delta) is allowed.

Mode 1067 = OFF (default): If any UR pair has been registered, downgrading the microcode to a version that does not support URxUR (including delta) is not allowed.

Notes:

1. This SOM is applied to enable microcode downgrade to a version that does not support URxUR (including delta) if the configuration where any UR pair has been registered is not URxUR (including delta).
2. Setting this SOM to ON allows microcode downgrade at sites where only 1 mirror is used in URxUR multi-target configuration without delta resync and cascade configuration (L or R site in multi-target, and P or R site in cascade), but the following phenomena occur after microcode downgrade. Make sure that the target storage system does not contain pairs of URxUR configuration.

   Phenomena:

   1. When the microcode is downgraded at S site (local or remote) in multi-target configuration, the pair between P site and the target S site cannot be resynchronized.
   2. When the pair between I site and R site in cascade configuration is resynchronized, the pair status cannot change from COPY to PAIR.
   3. When the microcode is downgraded at R site in cascade configuration, the pair between I site and R site cannot be resynchronized.

OFF

Both

1068

Common

This mode can detect and report a minor drive response delay early by severely checking drives.

Mode 1068 = ON: 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 HDD is not blocked. To block the HDD, SOM 144 also needs to be applied.

OFF

-

1097

Common

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

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

Mode 1097 = OFF (default): 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.

OFF

ON

-

1106

Dynamic Provisioning

Dynamic Tiering

This SOM is used to monitor the page usage rate of parity groups defined to a pool, and perform rebalance to balance the usage rate if the rate differs significantly among parity groups.

Mode 1106 = ON: The usage rate is checked once a day and the rebalance works if the rate is not even.

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

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: 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. For HDT pools, the term "total number of pages" is the number of pages assigned within each specific tier.

Examples:

1. In an HDP 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% and the difference in the rate between each parity group and the average is 10% at the maximum.

2. In an HDP 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% and the difference in the rate between each parity group and the average is 30% at the maximum.

3. In an HDT 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 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 rate between the parity group and the average is 5% at the maximum.

Note: This SOM is applied when balancing the usage rate is required at a customer site where the usage rate is not even.

OFF

-