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Hitachi Vantara Knowledge

Managing and maintaining pools

For details about monitoring pools with tiers, see Monitoring Dynamic Tiering pools.

Managing pools and DP-VOLs

Observe the following cautions when working with pools.

Caution
  • In one pool, if you need to perform two or more operations to edit several items, wait until the first task has been applied before performing the next task. If the next task is performed while the first task is being applied, the first task is canceled and the next task is applied to the storage system.
  • If you modified pool parameters by using Command Control Interface and then use Device Manager - Storage Navigator, click File > Refresh All to display the latest pool information before performing the next operation by using Device Manager - Storage Navigator. If you use Device Manager - Storage Navigator without refreshing the windows, the information updated by Command Control Interface might not yet be displayed on the Device Manager - Storage Navigator windows, so if you perform an operation the result might be different from what you expect.

Configuring the DP-VOL protection function options

Use this procedure to configure (enable or disable) the DP-VOL protection function options on an existing pool.

The DP-VOL protection function options are:

  • Protect V-VOLs when I/O fails to Full Pool Enable this option to protect the DP-VOLs using the pool from read and write requests when the pool usage reaches the full size.
  • Protect V-VOLs when I/O fails to Blocked Pool VOL Enable this option to protect the DP-VOLs using the pool from read and write requests when the pool-VOL is blocked.
NoteWhen either of these options is enabled for a Dynamic Provisioning pool that contains Thin Image pairs and snapshot data, if pool VOLs are blocked or the pool is full, only DP-VOLs are protected.

Before you begin

  • The Storage Administrator (Provisioning) role is required to perform this task.
  • The pool must meet all of the following conditions:
    • Data Retention Utility is installed.
    • The pool type is Dynamic Provisioning, Dynamic Tiering with Multi-Tier Pool enabled, or Active Flash.

Procedure

  1. Click Storage Systems, and expand the Storage Systems tree.

  2. Click Pools.

  3. In the Pools table, select the pool for which you want to enable or disable the DP-VOL protection function options.

  4. Click More Actions, and select Edit Pools.

  5. In the Edit Pools window, select the desired options for Protect V-VOLs when I/O fails to Blocked Pool VOL and Protect V-VOLs when I/O fails to Full Pool.

  6. Click Finish on the Edit Pools window.

    The Confirm window opens.
  7. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  8. Click Apply.

    If Go to tasks window for status is selected, the Tasks window opens automatically.

Storing Thin Image pair and snapshot data in a Dynamic Provisioning pool

You can create Thin Image (TI) pairs and store snapshot data in a Dynamic Provisioning pool.

The following figure shows a Dynamic Provisioning pool that contains Thin Image pair and snapshot data. When you use Dynamic Provisioning and Thin Image in one pool created from one parity group, the total capacity used by Dynamic Provisioning and Thin Image is required. Dynamic Tiering and active flash pools cannot be used for Thin Image pairs. TI pair and snapshot data in a DP pool

When you create Thin Image pairs in a Dynamic Provisioning pool, you can use the Suspend TI pairs when the depletion threshold is exceeded option to prevent Thin Image pair operations from affecting the DP-VOLs in the pool. When this option is enabled and the depletion threshold for the pool is exceeded, Thin Image pair operations are suspended, so the depletion threshold of the pool functions as the upper limit capacity for the Thin Image pairs.

  • When the depletion threshold is not exceeded:
    • Thin Image pairs can be created.
    • Thin Image pairs can be split.
  • When the depletion threshold is exceeded and the Suspend TI Pairs option is not enabled:
    • Thin Image pairs cannot be created.
    • Thin Image pairs can be split.
  • When the depletion threshold is exceeded and the Suspend TI Pairs option is enabled:
    • SIM code 62Exxx is output.
    • Thin Image pairs cannot be created.
    • Thin Image pairs cannot be split.

For a Dynamic Provisioning pool that contains Thin Image pairs and snapshot data, the capacity of snapshot data is included in the used capacity of the pool.

If you are concerned about operations when Dynamic Provisioning and Thin Image share a pool, it is recommended that you use separate pools for Dynamic Provisioning and Thin Image.

Controlling Thin Image pair behavior in a Dynamic Provisioning pool

Use this procedure to control whether Thin Image pairs are suspended when the free capacity of a Dynamic Provisioning pool that contains Thin Image pairs and snapshot data is depleted.

The Suspend TI pairs when depletion threshold is exceeded option enables you to stop Thin Image pair copy operations in a Dynamic Provisioning pool and prioritize the writing process to DP-VOLs when the free capacity of the pool is depleted. When this option is enabled and the pool used capacity exceeds the depletion threshold, SIM code 62Exxx is output. After this SIM code is output, if you split a Thin Image pair in the depleted pool, the operation fails and the pair is suspended by error (PSUE). You can restore the suspended Thin Image pairs when the pool used capacity has decreased below the depletion threshold and the SIM code has been cleared.

Before you begin

  • The Storage Administrator (Provisioning) role is required to perform this task.
  • The target pool must be a Dynamic Provisioning pool that contains Thin Image pairs and snapshot data.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. In the Pools table, select the pool you want to edit, click More Actions, and select Edit Pools.

  4. In the Edit Pools window, expand Options, and then select Suspend TI pairs when depletion threshold is exceeded.

  5. Select Yes to enable the option, or select No to disable the option.

  6. Click Finish.

  7. Check the settings in the Confirmation window, and then enter the task name in Task Name.

    You can enter up to 32 ASCII characters and symbols in all, except for \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  8. Click Apply.

    The task is registered. If you selected Go to tasks window for status, the Tasks window appears.

Viewing pool information

Use this procedure to view pool information.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

    The Pools window displays information about all of the pools in the storage system.
  3. To view details about a specific pool, expand Pools, and then select the desired pool.

    GUID-A9FFC4A9-508A-4696-BB03-2B148601BF25-low.png

Viewing formatted percentages for pool capacity

Use this procedure to view the formatted pool capacity.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools table, click the row of a pool with the free pool capacity you want to check.

  4. Click More Actions to select View Pool Management Status.

    The View Pool Management Status window appears.

Reasons to check pool capacity

The following are cases in which the free space of the pool is not formatted. In these cases, the free space of the pool may not increase:

  • Pools other than the selected pool are being formatted.
  • The pool usage level reaches the warning threshold or the depletion threshold.
  • The selected pool is blocked.
  • I/O loads to the storage system are high.
  • The cache memory is blocked.
  • Pool-VOLs in the selected pool are blocked.
  • Pool-VOLs that are external volumes in the selected pool are blocked.
  • Correction access executes to the pool-VOL in the selected pool.
NoteThe following are cases in which the formatted percentages for pool capacity may decrease:
  • New pages are being allocated.
  • LDEV format is being performed on the pool-VOL.
  • Correction copy is being executed.

Viewing the progress of rebalancing the usage level among parity groups

Use this procedure to view the progress of rebalancing the usage level among parity groups of a pool.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools table, click the row of a pool with you want to check the progress of rebalancing the usage level among parity groups.

  4. Click More Actions to select View Pool Management Status.

    The View Pool Management Status window appears.
    NoteThe following are cases in which the progress ratio may not increase:
    • The usage level is being rebalanced among the parity groups in pools other than the selected pool.
    • Tier relocation is performed.

Changing a pool name

Use this procedure to change a pool name.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools table, select the pool with the name you want to change.

  4. Click More Actions, and then select Edit Pools.

  5. In the Edit Pools window, in Pool Name, specify a name for this pool.

    1. In Prefix, type the characters that will become the fixed characters for the beginning of the pool name. The characters are case-sensitive.

    2. In Initial Number, type the initial number that will follow the prefix name.

  6. Click Finish.

    The Confirm window appears.
  7. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  8. Click Apply.

    If the Go to tasks window for status check box is selected, the Tasks window appears.

Recovering a blocked pool

You can perform failure recovery of a blocked pool. Ordinarily, you should not need to use this procedure. A recovered pool can be used, but the former data is lost.

The recovery time for pools varies depending on pool usage or DP-VOL usage. Allow roughly 20 minutes of recovery time for every 100 TB of pool or DP-VOL usage. Recovery time may vary depending on the workload of the storage system at the time of recovery.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. On the Pools tab, select the pool to be recovered.

  4. Click More Actions, and then select Restore Pools.

  5. In the Confirm window, confirm the settings.

  6. Enter a unique Task Name or accept the default.

    If Go to tasks window for status is checked, the Tasks window opens.

Changing a Dynamic Provisioning pool to a Dynamic Tiering pool

Use this procedure to change a Dynamic Provisioning pool to a pool for Dynamic Tiering or active flash.

Before you begin

  • The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools table, select the pool you want to edit.

  4. Perform one of the following to display the Edit Pools window.

    - Click More Actions and select Edit Pools. - Click Actions > Pool > Edit Pools to open the window.
  5. Check Multi-Tier Pool.

  6. Select Enable from the Multi-Tier Pool field.

  7. If active flash is used, select the Active Flash check box. If there is no pool volume whose drive type is SSD, the check box cannot be selected.

  8. Select the Tier Management check box.

  9. In the Tier Management field, select Auto or Manual.

    Normally Auto should be set.

    When you select Auto, monitoring and tier relocation can be automatically executed.

    When you select Manual, monitoring and tier relocation can be executed with the Command Control Interface commands or the Pools window.

    When you change the setting of Auto to Manual while monitoring and tier relocation is executing, it is cancelled.

  10. From the Cycle Time list, select the cycle of performance monitoring and tier relocation.

    Note
    • When you change the Cycle Time while performance monitoring and tier relocation are being executed, the setting becomes effective for the next cycle after the current cycle is complete.

      When you select 24 Hours (default):

      Monitoring and tier relocation is performed once a day. In the Monitoring Period field, specify the time of starting and ending of monitoring in 00:00 to 23:59 (default value).

    • If you specify the starting time later than the ending time, the monitoring continues until the time you specified as the ending time on the next day. Any time that is not in the specified range of the monitor period is not monitored.

    • You can view the information gathered by monitoring with Hitachi Device Manager - Storage Navigator and Command Control Interface.

    • When you change the time range of performance monitoring, the setting becomes effective from the next cycle after the cycle that is executing is complete.

      When you select any of 0.5 Hours, 1 Hour, 2 Hours, 4 Hours or 8 Hours:

      Performance monitoring is performed every duration you selected starting at 00:00.

      You cannot specify the monitoring period.

  11. Select the Monitoring Mode check box.

  12. From the Monitoring Mode options, select Period Mode or Continuous Mode.

    If you want to perform tier relocation using the monitor results from the prior cycle, select Period Mode. If you want to perform tier relocation weighted to the past period monitoring result, select Continuous Mode.
  13. Select the speed to use for page relocation in Relocation speed. You can set the speed to: 1(Slowest), 2(Slower), 3(Standard), 4(Faster), or 5(Fastest). The default is 3(Standard). If the speed specified is slower than 3(Standard), the data drive load is low when tier relocation is performed.

  14. Select the Buffer Space for New page assignment check box.

  15. In the Buffer Space for New page assignment text box, enter an integer value from 0 to 50 as the percentage (%) to set for each tier.

  16. Select the Buffer Space for Tier relocation check box.

  17. In the Buffer Space for Tier relocation text box, enter an integer value from 2 to 40 as the percentage (%) to set for each tier.

  18. Click Finish.

    The Confirm window appears.
  19. In the Task Name text box, enter the task name.

    You can enter up to 32 ASCII characters and symbols in all, except for \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  20. In the Confirm window, click Apply to register the setting in the task.

    If the Go to tasks window for status check box is selected, the Tasks window appears.

Estimating the required capacity of pool-VOLs with system area in a pool with data direct mapping enabled

If you want to expand a pool for which data direct mapping is enabled, you must free up space in the pool. Make sure that the estimated capacity of free space is available before expanding the pool.

Use the following mathematical formulas to estimate the capacity of free space required in the pool:

  • Formula 1:
    Required-free-space-for-a-pool-to-be-added-of-one-external-volume-of-the-data-direct-mapping-attribute [in MB] = (ceiling (pool-VOL-capacity [in MB] / 3,145,548 MB) * 4 pages * 42 MB) + ( ceiling (pool-VOL-capacity [in MB] / 42 MB) - floor (pool-VOL-capacity [in MB] / 42 MB) ) * 42MB 
    		  
  • Formula 2:
    Required-capacity-of-pool-VOL-with-system-area-in-one-pool-of-a-data-direct-mapping-attribute [in MB] = Total-of-calculated-values-by-the-Formula-1-for-each-volume + Management area (4200) [in MB] + 42 [in MB] 
    		  

where

  • ceiling: The value enclosed in ceiling( ) must be rounded up to the nearest whole number.
  • floor: The value enclosed in floor( ) must be rounded down to the nearest whole number.
Note

A DP-VOL with data direct mapping attribute uses the following capacities:

  • Mapped capacity uses multiple of 42 MB in the capacity of the pool volume as well as the capacity for one page (the area of the capacity other than multiples of 42 MB).

  • Control information (168 MB is used per 3,145,548 MB)

    The pool-VOL with the system area contains the one page capacity and control information.

Expanding a pool

To expand a pool (that is, increase the capacity of the pool), you add pool-VOLs to the pool.

Note
  • You cannot expand a pool while the pool is being shrunk.
  • When you add pool volumes to a Dynamic Tiering pool, tier relocation activities that are in process are stopped.
  • When you add pool volumes with available monitoring information to a Dynamic Tiering pool, tier relocation is performed. When you add pool volumes without available monitoring information to a pool, the page usage rate is averaged in the tier.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools table, select the pool you want to expand. You can expand only one pool at a time.

  4. Click Expand Pool.

  5. In the Expand Pool window, select the pool-VOL.

    1. Click Select Pool VOLs.

    2. In the Select Pool VOLs window, from the Available Pool Volumes table, select the pool-VOLs you want to assign, and then click Add.

      The selected pool-VOLs are registered in the Selected Pool Volumes table.

      Up to 1024 volumes can be added including the volumes already in the pool. You can use the Filter option to choose volumes by parameter.

      CautionFor details about adding of LDEVs carved from accelerated compression-enabled parity groups, see GUID-E3D4AB72-202B-4969-AC7C-829F7EFDDB4A.
      NoteIf necessary, perform the following steps:
      • From Filter option, select ON to filter the rows.
      • Click Select All Pages to select pool-VOLs in the table. To cancel the selection, click Select All Pages again.
      • Click Options to specify the unit of volumes or the number of rows to be viewed.
      • To set the tier rank of an external volume to a value other than Middle, select a tier rank from External LDEV Tier Rank, then click Add.
      • For a pool, you can add volumes whose Drive Type/RPM settings are the same and whose RAID Levels are different. For example, you can add the following volumes to the same pool:

        Volume whose Drive Type/RPM is SAS/15K and whose RAID Level is 5 (3D+1P)

        Volume whose Drive Type/RPM is SAS/15K and whose RAID Level is 5 (7D+1P)

      • When assigning a pool with DP-VOL enabled with full allocation, LDEVs cannot be added in the parity group with accelerated compression enabled.
    3. Click OK.

      The Select Pool VOLs window closes. The number of the selected pool volumes appears in Total Selected Pool Volumes, and the total capacity of the selected pool-VOL appears in Total Selected Capacity.
  6. Click Finish.

    The Confirm window appears.
  7. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  8. Click Apply.

    If Go to tasks window for status is selected, the Tasks window appears.

About decreasing pool capacity

When you want to decrease the capacity of, or shrink, a pool, you delete one or more pool volumes (pool-VOLs) from the pool. When a pool-VOL is removed from a pool, all of the used pages in the pool-VOL are moved to other pool-VOLs in the pool. If you delete the pool-VOL with the pool's system area, the used capacity and the management area are moved to other pool-VOLs in the pool. A pool must include one or more pool-VOLs.

For a pool to which a DP-VOL with the data direct mapping attribute disabled belongs, if a pool-VOL is released after the pool shrinking, the released pool-VOLs (LDEVs) are blocked. If the pool-VOLs (LDEVs) are blocked, format them before using them. If the blocked pool-VOL is an external volume, use Normal Format when formatting the volume. If the pool-VOL being deleted is an external volume and is disconnected during deletion, reconnect the external volume and then retry deleting the pool-VOL.

NoteYou cannot perform the following operations on a pool while the shrink pool operation is in process. Wait until shrinking completes, or stop the shrinking process.
  • Expand Pool
  • Shrink Pools
  • Edit Pools
  • Restore Pools

If you delete the pool-VOL with system area, a different system area pool-VOL will be assigned automatically according to the priority shown in the following table. If multiple pool-VOLs of the same drive type exist, the priority of each is determined by internal index of the storage system.

Priority

Data drive type

1

SAS7.2K

2

SAS10K

3

SAS15K

4

SSD

5

External volume

Notes on shrinking a Dynamic Provisioning pool

You cannot delete a pool-VOL from a Dynamic Provisioning pool under the following conditions:

  • If the pool-VOL is deleted, the total of the used pool capacity will exceed the pool depletion threshold.
  • If the pool-VOL with system area is deleted, the free space in the pool will be less than 4.2 GB.
  • In the case that pool-VOLs assigned to the accelerated compression-enabled parity group are deleted, the pool-VOLs cannot be deleted if the used capacity reserved for writing (after the deletion of pool-VOLs) exceeds the threshold due to deleting pool-VOLs.

    The used capacity reserved for writing (after deleting pool-VOLs) is calculated as follows:

    Used capacity reserved for writing (after deleting pool-VOLs) = Used capacity reserved for writing (before deleting pool-VOLs) + Total used capacity of pool-VOLs to be deleted × FMD Compression ratio 
    			 

    The used capacity reserved for writing (after deleting pool-VOLs) is larger than the used capacity reserved for writing (before deleting pool-VOLs). Because data stored in pool-VOLs belonging to the accelerated compression-enabled parity group is migrated in the following parity groups due to the shrinking of pool:

    • Parity group with accelerated compression is not supported (for example, SAS drives)
    • Parity group with accelerated compression is disabled
Notes on shrinking a Dynamic Tiering pool
  • You cannot delete a pool-VOL from a Dynamic Tiering pool under the following conditions:

    • If the pool-VOL is deleted, the total of the used pool capacity will exceed the pool depletion threshold.
    • If the pool-VOL with system area is deleted, the free space in the pool will be less than 4.2 GB.
  • When the pool-VOL is deleted, the pages contained in the deleted pool-VOL transfer to another pool-VOL in the same tier. If the used capacity in the tier exceeds Rate of Free Space Newly Allocated to, the overflowing pages transfer to another tier.
  • When pool-VOLs in the tier are empty, the appropriate tier is deleted.
  • Deleting the pool-VOL stops the tier relocation. The process resumes after the pool-VOL is deleted.
Notes on shrinking a Thin Image pool

You cannot delete a pool-VOL from a Thin Image pool under the following conditions:

  • If the pool-VOL is deleted, the used capacity of the pool will exceed the pool threshold.
  • If the pool-VOL with system area is deleted, the free space in the pool will be less than 4.2 GB.

Shrinking a pool

Use this procedure to shrink, or decrease the capacity of, a pool.

Note
  • You can shrink up to eight pools at the same time.
  • If you decrease the pool capacity soon after creating the pool or adding a pool-VOL, processing might take a while to complete.
  • If you decrease pool capacity by using Storage Navigator for the pool comprised of pool volumes assigned by parity groups with accelerated compression enabled, then you must delete the pool volumes that do not comprise the pool.
  • For the pool comprised of pool volumes assigned by parity groups with accelerated compression enabled, if you decrease pool capacity (that contains specified LDEVs) by using Storage Navigator or Command Control Interface, then the automatically adding pool volume function is disabled in the parity group of which the specified LDEVs belong.
  • You cannot decrease the pool capacity when any of the following operations is in process in the target pool:
    • When the pool is being created or deleted
    • When the pool capacity is being increased or decreased
    • When the pool is being recovered
    • When the Shrink Pool operation is being stopped
    • When the threshold is being changed
    • When zero pages are being reclaimed
    • When DP-VOLs are being created
    • When DP-VOL capacity is being increased
  • Do not issue a Command Control Interface command to decrease the capacity of a pool whose capacity is already in the process of being decreased.
  • If pool volumes to be removed are LDEVs that belong to the parity group which supports the accelerated compression function, the Shrink Pool operation takes a lot of time because the unallocated area is formatted and the pages are reclaimed.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools, and then select the pool that you want to shrink.

  3. On the Pool volumes tab, select the pool-VOL to be deleted.

    You can delete the pool-VOL when Yes is displayed in the Shrinkable column.
  4. Click Shrink Pool.

  5. In Task Name, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  6. In Estimated Result of Shrinking, review the details of Before Shrinking and After Shrinking, including the total pool capacity, the used pool capacity, and the free pool capacity.

  7. If the estimated result of shrinking is acceptable, click Apply.

    If Go to tasks window for status is selected, the Tasks window appears.

Stopping the decrease of pool capacity

Use this procedure to stop the decrease of pool capacity.

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Pools.

  3. From the Pools, select the pool with the capacity you want to stop decreasing.

  4. Click Stop Shrinking Pools.

  5. Click Finish.

    The Confirm window appears.
  6. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  7. Click Apply.

    If Go to tasks window for status is selected, the Tasks window opens.