System Option Modes

The mode can improve the host response time to be about within 6 seconds.

Note:

1. The mode applies when a drive response delay may affect business operations.

2. If Dynamic Sparing or Auto Correction Mode is used due to host I/O conflicts with copy processing, I/O watching time is 30 seconds even the mode is set to ON.

3. Even though System Option Mode 015 is set to ON, the function does not apply to SATA or NL-SAS drives.

Regarding the correction copy or the drive copy, in case ECCs/LRC PINs are set on the track of copy source HDD, mode 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 16*1) have been set on the track of copy source HDD, ECCs/LRC PINs (up to 16*1) 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 the maximum, the corresponding copy processing will be interrupted.

*1: The maximum number of ECCs/LRC PINs is as follows.

< For HUS VM>

73-03-01-00/00 or higher: 64

Earlier than 73-03-01-00/00: 16

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.

For HUS VM (SI for OPEN)

In response to the Restore instruction from the host, if neither Quick nor Normal is specified, the following operation is performed.

Mode 80 = ON:

Normal Restore (Reverse Copy) is performed.

Mode 80 = OFF:

Quick Restore is performed.

Notes:

1. This mode is applied when the specification for Restore of SI is switched between Quick (default) and Normal.

2. The performance of Restore differs depending on the Normal or Quick specification.

For Split or Resync request from the Mainframe host and Storage Navigator,

Mode 122 = ON:

By specifying Split or Resync, Steady/Quick Split or Normal/Quick Resync is respectively executed in accordance with Normal/Quick setting.

Mode 122 = OFF：

By specifying Split or Resync, Steady/Quick Split or Normal/Quick Resync is respectively executed in accordance with Normal/Quick setting.

For details, see the System Option Mode 122 sheet.

Notes:

(1) For HUS VM, this mode is applied to use scripts etc that are used on Lightning 9900 and Lightning 9900 V.

(2) Executing the pairresync command from RAID Manager may be related to the System Option Mode 087 setting.

(3) When performing At-Time Split from RAID Manager,

Set this mode to OFF or specify the environment variable HORCC_SPLT for Quick.

Otherwise, Pairsplit may turn timeout.

(4) The mode becomes effective after specifying Split/Resync following the mode setting. The mode function does not work if it is set during the Split/Resync operation.

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 mode 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: 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 mode depends on the microcode level:

• Default = ON: 80-04-27 and later (within 80-04-xx range), 80-05-05 and later
• Default = OFF: earlier than 80-04-27 (within 80-04-xx range), earlier than 80-05-05 (within 80-05-0x range)

Notes:

1. This mode should always be set to ON. This mode can be set to OFF only when the customer does not allow to set the mode to ON for a storage system already in production.
2. The mode is effective for the entire storage system.

ON (depends on microcode level)

144

The drive whose command response time is permanently delayed is blocked. At the same time, SSB=AE4A (total response time exceeds threshold) is reported. In this case, cache can become overloaded so that the storage system performance is degraded.

Mode 144 = ON: Check if there is a permanently delayed drive for each port, and block the corresponding port at the first time when all of the following conditions are met:

1. The total time for the drive to respond to 200 commands is 20 seconds or more.
2. The response time of the drive is two times or more longer than the average response time of the parity group (excluding the slow drive).
3. The drive is in one of the following statuses:

   - Normal

   - A source drive or a target drive (spare drive) during drive copy.

   - A target drive (not spare drive) during copy back.

   - A target drive (spare drive) during correction copy.

Mode 144 = ON: Checking for delayed drives is not performed.

The default setting for this mode depends on the microcode level:

• Default = ON: 80-04-27 and later (within 80-04-xx range), 80-05-05 and later, 83-04-03 and later
• Default = OFF: earlier than 80-04-27 (within 80-04-xx range), earlier than 80-05-05 (within 80-05-0x range), earlier than 83-04-03

Note: If there are multiple response-delayed drives in the same parity group, only the first one is blocked.

ON (depends on microcode level)

Mode 310 = ON:

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

Mode 310 = OFF:

The monitoring timer for MP hang-up is 8 seconds.

Notes:

(1) This mode applies to a site where strict host response performance is required.

(2) If a hardware failure occurs when the mode is set to ON, the time until MPB blockage is determined is shorter than usual.

Mode 448 = ON: (Enabled)

If the SVP detects a blocked path, the SVP assumes that an error occurred, and then immediately splits (suspends) the mirror.

Mode 448 = OFF: (Disabled)

If the SVP detects a blocked path and the path does not recover within the specified period of time, the SVP assumes that an error occurred, and then splits (suspends) the mirror.

Note:

The mode 448 setting takes effect only when mode 449 is set to OFF.

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

Mode 449 = ON

On MCU side, checking read journal disruption from RCU is disabled, and monitoring read journal failures is disabled on RCU side.

Mode 449 = OFF

Detecting communication failures between MCU and RCU is enabled.

Notes:

(1) The mode applies at sites where disabling the detection of communication failures between MCU and RCU in UR configuration is required.

(2) For USP/NSC, the default setting is OFF with versions from 50-03-95-00/00 to 50-04-31-00/00, and is ON with versions 50-04-40-00/00 and later.

(3) When the mode is set to ON, System Option Mode 448 does not work.

(4) The mode setting is not changed by microcode upgrade.

(5) The mode is not effective for remote paths between Initiator port on MCU and Target port on RCU.

(6) While a path from 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 the Maintenance Manual.

CLPR (Function of Virtual Partition Manager) partitions the cache memory in the disk subsystem 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 System Option Mode 454 is set to ON or OFF.

Mode 454 = OFF:

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:

(for HUS VM)

(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 Mode 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:

(for HUS VM)

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

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, it is limited to set Mode 454 to ON only when a CLPR has constant high workload and it gives priority to I/O performance in a CLPR with low workload than host I/O halt in the CLPR with high workload.

Notes:

(1) When this System Option Mode 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 System Option Mode to ON only when the overloaded state of a specific CLPR would not affect other CLPRs.

In the case where the HUR 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 either. Therefore it is recommended to set this System Option Mode 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) may occur.

(1) High Speed LDEV Format for External Volumes

The high speed LDEV format for external volumes is available by setting System Option Mode 457 to ON. If System Option Mode 457 is ON, when selecting the external volume group and performing the LDEV format, any Write processing on the external LUs will be skipped. However, if the emulation type of the external LDEV is a mainframe system, the Write processing for mainframe control information only will be performed after the write skip.

(2) Support for Mainframe Control Block Write GUI

In case of System Option Mode 457 On, the high speed LDEV format for external volumes was supported at V03. Since V04, Control Block Write of the external LDEVs in Mainframe emulation has been supported by Storage Navigator (GUI).

- In case the LDEV is not written with data “0” before performing the function, the LDEV format may fail.

- After the format processing, make sure to set System Option Mode 457 to OFF.

PAIR → PSUS(SP) → PSUS: System Option Mode 459 function is running at copy pending from P-VOL to S-VOL such as PSUS(SP) → PSUS. Please refer additional TAB of mode list.

Mode 459 = ON:

Waits for cache memory to completely destage the DKC S-Vol to the External Volume S-Vol before changing pair status to SUSPEND.

Mode 459 = OFF:

The status changes to SUSPEND as soon as all the delta data is copied to S-Vol cache. The status does not wait for cache to destage to the S-Vol external volume.

Universal Replicator recommends the line band of 100 Mbps or more for the path between Main and Remote. However, when a customer uses the line band of around 10 Mbps, operation on UR cannot be properly processed. As a result, many retries occur and UR may suspend. This mode is provided to guarantee the line band of at least 10 Mbps for proper system operation.

Mode 466 = ON:

The line band of 10 Mbps or more is available. The JNL read is performed with 4-multiplexed read size of 256 KB.

Mode 466 = OFF:

The same as the conventional operation. The line band of 100 Mbps or more is available. The JNL read is performed with 32-multiplexed read size of 1 MB by default.

Note that the line band can be changed from the window for changing JNL group options.

In case of using the following features, the current copy processing slows down if the dirty percentage is 60% or larger, and it stops if the dirty percentage is 75% or larger. Mode 467 is to prevent the dirty percentage from over 60% so that the host performance is not affected.

The default setting is different according to models and versions. For details, see spreadsheet "Default Setting of Mode 467".

Mode 467 = ON:

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 mode must always be set to ON when using an external volume as the secondary volume of any of the above-mentioned PPs for copy.

2. It takes longer to finish the copy processing because it stops for prioritizing the host I/O performance.

3. This mode supports background copy only. The processing to copy the pre-update data to the S-VOL, which occurs when overwriting data to un-copied slots of P-VOL in Split processing or reading or writing data to un-copied slots of S-VOL, is not supported.

4. 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 where ShadowImage / ShadowImage for z/OS / FCV2 / Copy-on-Write Snapshot / Volume Migration pairs belong to exceeds the threshold, the copy operation is stopped.

Since the SIM-RC(*) that are generated when the usage rate of Pool used by Snapshot exceeds the threshold value can be resolved by users, basically they are not reported to the maintenance personnel.

This option is used to inform maintenance personnel of these SIMs that are basically not reported to maintenance personnel in case these SIMs must be reported to them.

* SIMs reported by setting the mode to ON are as follows.

- HUS VM:

SIM-RC 601xxx (Pool utilization threshold excess)/ 603000 (SM Space Warning)

Mode 471 = ON:

This kind of SIMs is reported to maintenance personnel.

Mode 471 = OFF:

This kind of SIMs is not reported to maintenance personnel.

Notes:

Set this mode to ON when it is required to inform maintenance personnel of the SIM-RC(*).

* SIMs reported by setting the mode to ON are as follows.

- HUS VM:

SIM-RC 601xxx (Pool utilization threshold excess)/ 603000 (SM Space Warning)

UR initial copy performance can be improved by issuing a command from Raid Manager/BC Manager to execute a dedicated script consists of UR initial copy (Nocopy), UR suspend, TC (Sync) initial copy, TC (Sync) delete, and UR resync.

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:

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.

Notes:

1. Set this mode for both MCU and RCU.

2. When the mode is set to ON;

- Execute all of pair operations from Raid Manager/ BCM.

- Use a dedicated script.

- Initial copy operation is prioritized over update I/O. Therefore, the processing speed of the update I/O slows down by about 15μs per command.

3. If this mode is set to ON, the processing speed of update I/O slows down by about 15μs per command, version downgrade is disabled, and Take Over is not available.

4. If the mode is not set to ON for both or either sides, the behavior is as follows.

- Without setting on both sides: Normal UR initial copy performance.

- With setting on MCU/without setting on RCU: TC Sync pair creation fails.

- Without setting on MCU/with setting on RCU: The update data for P-VOL is copied to the S-VOL in synchronous manner.

5. While the mode is set to ON, make sure not to perform micro-program downgrade to an unsupported version.

6. While the mode is set to ON, make sure not to perform the Take Over function.

7. The mode cannot be applied to a UR pair that is the 2nd mirror in URxUR multi-target configuration or URxUR cascade configuration. If applied, TC pair creation is rejected with SSB=CBEE output.

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

The HUR Differential Resync configuration is required.

Mode 506 = ON:

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 mode 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 subsystem used for the Delta Resync operation.

This option is used to allow Quick Restore for external volumes with different Cache Mode settings.

Mode 561 = ON:

Quick Restore for external volumes with different Cache Mode settings is prevented.

Mode 561 = OFF:

Quick Restore for external volumes with different Cache Mode settings is allowed.

When this option 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:

Progress is updated when the progress rate exceeds the previous level.

Notes:

1. Set this option 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 Storage Navigator (It indicates “-“ until just before the completion and at the last it changes to 100%).

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 mode can be set online.
2. The micro-programs on both MCU and RCU must support this mode.
3. This mode should be set when requested by the user.
4. Setting this mode 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. Do not set this mode if the primary or secondary system is connected to USP V/VM with microcode earlier than 60-02-xx-xx/xx. If this mode is applied and the write-pending rate reaches 60%, pair suspend might occur.
7. As this mode is enabled per storage system, in an environment where TC and GAD are used, this 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.

This option 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:

Read JNL or JNL Restore is not prevented when the Write Pending rate on RCU exceeds 60% (the same as before).

Notes:

1. This mode can be set online.

2. This mode 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 RAID 500 is used on P-VOL side, the mode cannot be used. If the mode is set to ON, SSB=8E08 on P- VOL side and SSB=C8D1 on S-VOL side may frequently be output.

This mode is available to enable or disable the QoS function.

Mode 696 = ON:

QoS is enabled. (In accordance with the Share value set to SM, I/Os are scheduled. The Share value setting from RMLIB is accepted.)

Mode 696 = OFF:

QoS is disabled. (The Share value set to SM is cleared. I/O scheduling is stopped. The Share value setting from host is rejected.)

Note:

1. Set this mode to ON when you want to enable the QoS function.

This option is used to issue the Read command at the LU discovery operation using UVM.

Mode 701 = ON:

The Read command is issued at the LU discovery operation.

Mode 701 = OFF:

The Read command is not issued at the LU 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 the mode to ON.

2. When this option is set to ON, it takes longer time to complete the LU discovery. The amount of time depends on external storages.

3. With this system option OFF, if searching for external devices with VMA set, the VMA information cannot be read.

4. When the mode is set to ON while the following conditions are met, the external volume is blocked.

(a) HUS VM is used on the storage system.

(b) An external volume to which Nondisruptive Migration (NDM) attribute is set exists.

(c) The external volume is reserved by the host.

5. 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.

6. Set the mode to OFF when the following conditions are met.

(a) HUS VM is used on the storage system.

(b) An external volume to which Nondisruptive Migration (NDM) attribute is set exists.

To reduce the chance of MIH, this mode can reduce the priority of ShadowImage, Volume Migration, or Resync copy internal IO requests so that host IO has a higher priority. This mode 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 mode 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.

When a parity group is uninstalled or installed, the following operation is performed accordingly.

Mode 721 = ON:

When a parity group is uninstalled or installed, neither the LED of the HDD for uninstallation lights up, nor the instruction message for removing the HDD appears. Also, the windows other than that of parity group, such as DKA or DKU, are unavailable to select.

Mode 721 = OFF:

When a parity group is uninstalled or installed, the operation is as before; the LED of the HDD lights up, and the HDD must be unmounted and remounted.

Notes:

1. When the RAID level or emulation type is changed for the existing parity group, this option should be applied only if the HDD mounted position remains the same at the time of the parity group uninstallation or installation.

2. After the operation using this option is completed, the mode must be set back to Off; otherwise, the LED of the HDD to be removed will not light up at subsequent parity group uninstalling operations

This option determines an action when Not Ready is returned from the external volume.

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 blockade, may be repeated.

From version 60-05-06-00/00, the following is added.

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

Mode 725 = OFF:

When Not Ready is returned 3 times in 3 minutes, the path is blocked and the path status cannot be automatically recovered (Response error blockade).

Notes:

1. For HUS VM:

(1) Applying this System Option Mode is prohibited when USP V/VM is used as an external subsystem and its external volume is DP-VOL.

(2) Applying this System Option Mode is recommended when the above condition (1) is not met and SUN storage is used as an external storage.

(3) Applying this System Option Mode is recommended when the above condition (1) is not met and EMC CX series, VNX series, or Fujitsu Fibre CAT CX series is used as an external storage.

(4) Applying this System Option Mode 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 subsystem.

2. While USP V/VM is used as an external subsystem and its volume is DP-VOL, if some Pool-VOLs constituting the DP-VOL are blocked, a phenomenon of external path blockade and recovery occurs repeatedly.

3. In the case that a virtual volume mapped by UVM is set to pool-VOL and used as DP-VOL in local subsystem, this System Option Mode can be applied without problem.

To set the Protect attribute for the target DP-VOL using Data Retention Utility (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.

Mode 729 = ON: To set the Protect attribute for the target DP-VOL using 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 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.
   • 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. With 83-01-21-x0/00 and later, the Virtual Volume Protection (VVP) function is supported. VVP 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. With or 83-01-21-x0/00 and later, 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 as that of setting the mode to OFF even when the SOM is set to ON.

This option enables to suspend Volume Migration or Quick Restore operation during LDEV-related maintenance.

USP V/VM:

Mode 733 = ON:

Volume Migration or Quick Restore operation during LDEV-related maintenance is suspended.

Mode 733 = OFF:

Volume Migration or Quick Restore operation during LDEV-related maintenance is not suspended.

VSP and later models, HUS VM and later models:

Mode 733 = ON:

Volume Migration or Quick Restore operation during LDEV-related maintenance is not suspended

Mode 733 = OFF:

Volume Migration or Quick Restore operation during LDEV-related maintenance is suspended.

Notes:

1. (USP V/VM) This option is recommended as functional improvement to avoid maintenance failures. In some cases of a failure in LDEV-related maintenance without setting the option, Storage Navigator operations may be unavailable.

2. (USP V/VM) There is the potential for LDEV-related maintenance activities to fail when Volume Migration and Quick Restore is active without setting the option.

3. Note that behavior when the mode is set to ON and OFF is reversed between USP V/VM and VSP and later/HUS VM and later.

4. (USP V/VM) This option should be applied when Volume Migration or Quick Restore operation can be suspended during LDEV-related maintenance.

5. (USP V/VM) If virtual volume capacity expansion operation conflicts with Volume Migration or Quick Restore operation, the virtual volume capacity expansion operation may fail.

6. (VSP and later/HUS VM and later) This mode should be applied to perform Volume Migration or Quick Restore during maintenance operation.

7. (VSP and later/HUS VM and later) Set mode 733 to ON if you want to prioritize the Volume Migration or Quick Restore operation over maintenance activities. In this case, maintenance activities may fail when the Volume Migration or Quick Restore operation works during the maintenance activities.

8. (VSP and later/HUS VM and later) An LDEV-related maintenance operation such as LDEV installation/removal may fail when Volume Migration or Quick Restore takes place.

When exceeding the pool threshold, the SIM is reported as follows.

Mode 734 = ON:

A SIM is reported at the time when the pool usage rate exceeds the pool threshold (warning, system, or depletion). Once the pool usage rate falls below the pool threshold, and then exceeds again, the SIM is reported again. If the pool usage rate continues to exceed the warning threshold and the depletion threshold, the SIM (SIM-RC625000) is repeatedly reported every eight (8) hours until the pool usage rate falls below the depletion threshold.

Mode 734 = OFF:

A SIM is reported at the time when the pool usage rate exceeds the pool threshold (warning, system, or depletion). Once the pool usage rate falls below the pool threshold, and then exceeds again, the SIM is reported again. The SIM is not reported while the pool usage rate continues to exceed the warning threshold and the depletion threshold.

Notes:

1. This option is turned ON to prevent the Write I/O operation from being unavailable due to pool full.

2. If the pool threshold exceeding SIM occurs frequently, other SIMs may not be reported.

3. Though turning on this option can increase the warning effect, if measures such as adding a pool fail to be done in time so that the pool becomes full, system option mode 729 can be used to prevent file systems from being destroyed.

4. Turning on system option mode 741 can provide the SIM report to not only the users but also the service personnel.

The option 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:

SIM is not reported to the service personnel

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.

- if Storage Navigator isn’t periodically activated.

2. When Mode 734 is turned OFF, SIM-RC625000 is not reported; accordingly the SIM is not reported to the service personnel even though this option is ON.

This option enables to change the area where the information is obtained as the Characteristic1 item from SYMMETRIX.

Mode 745 = ON:

(1) The area where the information is obtained as the Characteristic1 item from SYMMETRIX is changed.

(2) 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:

(1) The area where the information is obtained as the Characteristic1 item from SYMMTRIX is set to the default.

(2) 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 option is applied when the SYMMETRIX of EMC is connected using UVM.

2. Enable the setting of EMC SCSI Flag SC3 for the port of the SYMMETRIX storage of EMC connected with USP V/VM 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 mode may not be achieved.

3. If you want to enable this mode immediately after setting, perform Check Paths on each path one by one for all the external ports connected to the SYMMETRIX storage of EMC. 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.

4. If the Check Paths is performed while ShadowImage for z/OS pair and FlashCopy Mirror pair are defined in the specified volume, the Check Paths operation is rejected with a message, “605 2518”. If ShadowImage for z/OS pair and FlashCopy Mirror pair are defined in the specified volume, do not perform Check Paths but wait until the display is automatically changed.

This mode disables the DP Rebalance function and the DT Tier relocation function which allow the HDDs of all ECC Groups in the pool to share the load.

Mode 749 = ON:

The DP Rebalance function and the DT Tier relocation functions are disabled.

Mode 749 = OFF:

The DP Rebalance function and the DT Tier relocation functions are activated.

Notes:

1. This option 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 the mode is set to ON fails. To delete pool VOLs, set the mode to OFF.

Setting this mode to ON or OFF to disable or enable outputting In-band audit logs.

Mode 757 = ON:

In-band audit log is not output.

Mode 757 = OFF:

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 option 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 mode to OFF.

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

The mode is applied to TC Sync (83-01-01-x0/00 and higher) and GAD (83-01-21-x0/00 and higher).

Mode 784 = ON:

The MIH time of RIO is internally reduced so that, even though a path failure occurs between DKCs 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:

The operation is processed in accordance with the TC Sync specification.

Notes:

(1) The mode is applied to the environment where OPEN host time-out time is set to 15 seconds or less.

(2) The mode is applied to reduce RI/O MIH time to 5 seconds.

(3) This function is available for all the TC Sync and GAD pairs on the subsystem, unable to specify the pairs that are using this function or not.

(4) To apply the mode to TC Sync, both MCU and RCU must be HUS VM and micro-program must be the support version on both sides. If either one of MCU or RCU is USP V/VM, the function cannot be applied.

(5) For a TC Sync or GAD pair with the mode 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 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 DKCs, Open server time-out may occur.

(7) If an MP to which the path between DKCs belongs is overloaded, switching to an alternate path delays and 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, time-out may occur due to response time accumulation for each RI/O retried within 5 seconds.

(9) Even though the mode is set to ON, if Open host time-out time is set to 10 seconds or less, time-out may occur due to a path failure between DKCs.

(10) Operation commands are not available for promptly switching to an alternate path.

(11) The mode 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 Sync pairs are suspended or deleted.

(13) See System Option Mode 784 sheet for operational specifications in each combination of MCU and RCU of TC.

(14) For GAD pairs, the mode is effective if the microcode is in a version that supports GAD.

(15) The mode does not support paths between DKCs using iSCSI in VSP Gx00/Fx00. (Configuration where DKC paths of Fibre and iSCSI coexist is not supported.)

While a DP pool VOL is blocked, if a read or write I/O is issued to the blocked pool VOL, this mode can enable the Protect attribute of DRU for the target DP-VOL.

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

Notes:

1. This mode 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. With 83-01-21-x0/00 and later, the Virtual Volume Protection (VVP) function is supported. VVP 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.

By switching the mode to ON/OFF when ShadowImage is used with System Option Mode 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:

The copy processing is stopped when the amount of dirty data is over 60%.

For details, see the System Option Mode 855 sheet.

Notes:

1. This mode is applied when all the following conditions are met.

- ShadowImage is used with System Option Mode 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 mode is available only when System Option Mode 467 is set to ON.

3. If workload of the copy target parity group is high, the copy processing may not be improved even if this mode is set to ON.

This option enables or disables to limit the cache allocation capacity per MPB (VSP / VSP G1000) or MPU (HUS VM) to within the prescribed capacity (*) except for Cache Residency.

*: 128 GB (VSP/HUS VM), 256 GB (VSP G1000).

Mode 857 = ON:

The cache allocation capacity is limited to within the prescribed capacity.

Mode 857 = OFF:

The cache allocation capacity is not limited to within the prescribed capacity.

Notes:

(1) This mode is applied to stabilize the performance by preventing paging of PM control information from occurring. For details, refer to the section of Virtual Partition Manager in the guideline.

(2) The cache hit rate may decrease.

(3) The cache allocation capacity per MPB/MPU is limited to within the prescribed capacity.

All-page reclamation (discarding all mapping information between DP pool and DP volumes) is executed in DP-VOL LDEV format. This new method is enabled or disabled by setting the mode to ON or OFF.

(Version 83-04-01-x0/00 or later) Mode 867 = ON:

LDEV format of the DP-VOL is performed with page reclamation.

(Version 83-03-xx or earlier) Mode 867 = OFF:

LDEV format of the HDP-VOL is performed with 0 data writing.

Notes:

1. The mode is applied from factory shipment.

2. Do not change the setting of the mode during DP-VOL format.

3. If the setting of the mode is changed during DP-VOL format, the change is not reflected to the format of the DP-VOL being executed but the format continues in the same method.

The mode enables or disables the background format function performed on an unformatted area of a DP/DT/TI*1 pool.

*1: The background format function for a TI pool is only available for V01+1 (73-01-31-00/00) or higher.

* For the information of operating conditions, refer to Provisioning Guide for Open Systems.

Mode 896 = ON:

The background format function is disabled.

Mode 896 = OFF:

The background format function is enabled.

Notes:

1. <HUS VM> The mode is applied when a customer requires disabling the background format for a DP/DT/TI*1 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 42MB/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 the mode setting, the format progress is initialized and the entire area become unformatted.

By the combination of System Option Mode 897 and 898 setting, the expansion width of Tier Range upper I/O value (IOPH) can be changed as follows.

Mode 897 = ON:

System Option Mode 898 is OFF: 110%+0IO

System Option Mode 898 is ON: 110%+2IO

Mode 897 = OFF (Default)

System Option Mode 898 is OFF: 110%+5IO (Default)

System Option Mode 898 is ON: 110%+1IO

By setting the System Option Modes to ON to lower the upper limit for each tier, the gray zone between other tiers becomes narrow and the frequency of page allocation increases.

Notes:

1. Apply the mode when the usage of upper tier is low and that of lower tier is high.

2. The mode must be used with System Option Mode 898.

3. Narrowing the gray zone increases the number of pages to migrate between tiers per relocation.

4. When Tier1 is SSD while System Option Mode 901 is set to ON, the effect of System Option Mode 897 and 898 to the gray zone of Tire1 and Tier2 is disabled and the System Option Mode 901 setting is enabled instead. In addition, the settings of System Option Mode 897 and 898 are effective for Tire2 and Tier3.

Please also see spreadsheet "System Option Mode_897_898_901" for more details about the relations between Mode 897, 898 and 901.

By the combination of System Option Mode 898 and 897 setting, the expansion width of Tier Range upper I/O value (IOPH) can be changed as follows.

Mode 898 = ON:

System Option Mode 897 is OFF: 110%+1IO

System Option Mode 897 is ON: 110%+2IO

Mode 898 = OFF (Default):

System Option Mode 897 is OFF: 110%+5IO (Default)

System Option Mode 897 is ON: 110%+0IO

By setting the System Option Modes to ON to lower the upper limit for each tier, the gray zone between other tiers becomes narrow and the frequency of page allocation increases.

Notes:

1. Apply the mode when the usage of upper tier is low and that of lower tier is high.

2. The mode must be used with System Option Mode 897.

3. Narrowing the gray zone increases the number of pages to migrate between tiers per relocation.

4. When Tier1 is SSD while Mode 901 is set to ON, the effect of system option mode 897 and 898 to the gray zone of Tire1 and Tier2 is disabled and the Mode 901 setting is enabled instead. In addition, the settings of Mode 897 and 898 are effective for Tire2 and Tier3.

Please also see spreadsheet "System Option Mode_897_898_901" for more details about the relations between System Option Mode 897, 898 and 901.

In combination with the system option mode 900 setting, whether to execute and when to start the I/O synchronous copy change as follows.

Mode 899 = ON:

System option mode 900 is ON: I/O synchronous copy starts without retrying Volume Migration.

System option mode 900 is OFF: I/O synchronous copy starts when the threshold of Volume Migration retry is exceeded. (Recommended).

Mode 899 = OFF:

System option mode 900 is ON: I/O synchronous copy starts when the number of retries reaches half of the threshold of Volume Migration retry.

System option mode 900 is OFF: Volume Migration is retired and I/O synchronous copy is not executed.

Notes:

1. This mode 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.

In combination with system option mode 899 setting, whether to execute and when to start the I/O synchronous copy change as follows.

Mode 900 = ON:

System option mode 899 is ON: I/O synchronous copy starts without retrying Volume Migration.

System option mode 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:

System option mode 899 is ON: I/O synchronous copy starts when the threshold of Volume Migration retry is exceeded. (Recommended)

System option mode 899 is OFF: Volume Migration is retired and I/O synchronous copy is not executed.

Notes:

1. This mode 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.

By setting the mode 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 the 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 the 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 x 110% + 5 [IOPH].

Notes:

1. This mode is applied when pages with the maximum capacity need to be allocated to tier1 (drive type is SSD) with DT or DTz.

2. When Tier1 is SSD while System Option Mode 901 is set to ON, the effect of System Option Mode 897 and 898 to the gray zone of Tire1 and Tier2 is disabled and the System Option Mode 901 setting is enabled instead. In addition, the settings of System Option Mode 897 and 898 are effective for Tire2 and Tier3.

3. The following is recommended when applying System Option Mode 901.

The actual I/O value (total number of I/Os of all tiering policies) < the performance potential value of Tier 1*1 x 0.6

*1: The performance potential value of Tier 1 displayed on Monitor information by using Dx-ray.

Please also see spreadsheet "System Option Mode 897_898_901" for more details about the relations between System Option Mode 897, 898 and 901.

By setting the mode 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:

No restriction on the number of pages to be migrated at tier relocation (existing specification).

Notes:

1. This mode is applied when

- Dynamic Tiering for Mainframe is used (including multi platforms configuration).

- the requirement for response time is severe.

2. The number of pages to be migrated per unit time at tier relocation decreases.

The mode can change CM capacity allocated to MPBs with different workload.

Mode 908 = ON:

Difference in CM allocation capacity among MPBs with different workload is large.

Mode 908 = OFF:

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 the mode 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. System option mode 908 cannot be used with system option mode 933. When system option mode 933 is set to ON, the function of system option mode 908 is canceled even though system option mode 908 is ON.

4. This mode is effective for a CLPR. Therefore, when setting the mode 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 the mode to ON/OFF.

When the mode is set to ON, all of the zero data page reclamation operations in processing are stopped. (Also the zero data page reclamation cannot be started.)

* Zero data page reclamation by WriteSame and UNMAP functions, and IO synchronous page reclamation 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:

The zero data page reclamation is performed.

See the system option mode 930 sheet for relationship with system option mode 755.

Notes:

(1) The mode is applied when stopping or disabling zero data page reclamation by user request is required.

(2) When the mode is set to ON, the zero data page reclamation does not work at all.

* Zero data page reclamation by Write Same and UNMAP, and IO synchronous page reclamation can work.

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

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

By setting the mode to ON, DT monitoring data is collected even if the pool is a DP pool.

Mode 937 = ON:

DT monitoring data is collected even if the pool is a DP pool.

Only Manual execution mode and Period mode are supported.

Mode 937 = OFF:

DT monitoring data is not collected if the pool is a DP pool

Notes:

1. The mode is applied when DT monitoring data collection is required in DP environment.

2. When DT is already used, do not set the mode to ON.

3. For DT monitoring data collection, shared memory for DT must be installed. For details, see the system option mode 937 sheet.

4. If monitoring data collection is performed without shared memory for DT installed, an error is reported and the monitoring data collection fails.

5. Before removing the shared memory for DT, set the mode to OFF and wait for 30 minutes.

6. Tier relocation with monitoring data collected when the mode is set to ON is disabled.

7. When DP is converted into DT (after purchase of PP license), the collected monitoring data is discarded.

8. Before downgrading the micro-program to an unsupported version, set system option mode 937 to OFF and wait for at least 30 minutes.

The mode 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) The mode 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 the mode 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 may occur repeatedly.

This mode disables journal copy.

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

(a) Write Pending rate of MP blade for which journal ownership is defined is 25% or higher.

(b) Initiator operating rate of MP blade for which journal ownership is defined is 40% or higher.

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

Notes:

1. This mode applies when (a) and (b), or (a) and (c) are met.

   (a) Usage of journal volume in the UR secondary site is high.

   (b) The configuration contains multiple primary and secondary sites.

   (c) A consistency group configuration contains both open and mainframe hosts.

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 mode.
3. When the host write speed is faster than the JNL copy speed, the usage rate of the master journal increases.
4. This mode is effective within the range of each CLPR. Therefore, an operation target LPRxx (xx= 00 to 31) needs to be selected before setting this mode to ON/OFF.

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

The mode changes the processing for a group operation with GAD CTG.

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) The mode 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 the mode because setting the mode may affect the host I/O performance.

(2)The MP usage rate increases during status change of all pairs in a CTG. For approximate percentage increase in MP usage rate, see sheet "System Option Mode 1070".

This mode is used to disable background unmap during microcode downgrade from a version that supports pool reduction rate correction to a version that does not support the function.

Mode 1093 = ON:

Background unmap cannot work.

Mode 1093 = OFF (default):

Background unmap can work.

Notes:

The mode is applied when downgrading microcode from a version that supports pool reduction rate correction to a version that does not support the function is disabled.

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

Mode 1097 = ON:

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:

The mode disables the warning LED to blink when specific SIMs are reported.

This mode 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: 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% and the difference in the 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 `G3 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 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 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:

(1) The mode is applied when balancing the usage rate is required at a customer site where the usage rate is not even.

When this mode is set to ON, data is initialized without using metadata at LDEV format for a virtual volume with Capacity Saving enabled.

Mode 1115 = ON:

When LDEV format is performed for a virtual volume whose capacity saving setting is Compression, the data is initialized without using the metadata.

Mode 1115 = OFF (default):

When LDEV format is performed for a virtual volume whose capacity saving setting is Compression, normal formatting is performed, but if one of the following conditions is met, the data is initialized without using metadata.

- There is a pinned slot.

- The capacity saving status is “Failed”.

- The virtual volume is blocked (Normal restore cannot be performed).

Note:

(1) The mode is applied to recover a blocked pool volume in a pool to which a virtual volume whose capacity saving setting is Compression belongs.

For the information of setting timing, refer to the procedure for blocked pool volume recovery in the Maintenance Manual.

(2) The processing time increases with increase in pool capacity. (*1)

(3) Do not change the mode setting during LDEV format for a virtual volume whose capacity saving setting is Compression. If the setting is changed, the processing cannot be performed correctly and may end abnormally depending on the timing.

(4) The mode is effective only for LDEV format for a virtual volume whose capacity saving setting is Compression, so that there is no side effect in relation to user data, but the processing may take more time than that when the mode is set to OFF depending on the pool capacity. Therefore, basically do not use the mode for cases other than pool volume blockage recovery.

*1: Estimate of processing time

Processing time (minute) = (pool capacity (TB)/40) + 5

* If the result of dividing pool capacity by 40 has decimal places, round it up to an integral number.

* The processing finishes early if there is less capacity of allocated pages.

This mode is used to disable the ENC reuse function.

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 mode is applied when you want to disable the ENC reuse function.

This mode is used to downgrade the microcode as follows while capacity saving is enabled:

• VSP G1000, VSP G1500, VSP F1500: From 80-05-05-00/00 or later to 80-05-01-00/00 or later
• VSP Gx00 models, VSP Fx00 models: From 83-04-03-x0/00 or later to 83-04-01-x0/00 or 83-04-02-x0/00

New control information is added with 80-05-05/83-04-03 for the inflow control processing when capacity saving is enabled. However, it must be guaranteed that the area is not used when the microcode version is 80-05-01/83-04-01 or later. This system option mode disables the control information added with 80-05-21/83-04-21 when capacity saving is enabled to enable microcode downgrade.

Mode 1119 = ON: The control information is not used when capacity saving is enabled.

Mode 1119 = OFF: The control information is used when capacity saving is enabled.

Notes:

1. Set this mode to ON when the microcode downgrade described above is performed, even if capacity saving is not currently in use but has been used before.
2. After the microcode downgrade is complete, make sure to set the mode to OFF.
3. The mode is effective for the entire storage system.
4. The write performance might degrade when this mode is ON.