V-VOLs with data direct mapping enabled

Provisioning Guide for Open Systems for VSP One Block 85
Version
10.5.x
File Size
3643 KB
Audience
anonymous
Part Number
MK-26VSP1B033-03
ft:lastEdition
2026-06-23

By using a V-VOL for which data direct mapping is enabled, you can create a mapping of an external volume larger than 4 TB without having to change its capacity as a V-VOL of the local storage system.

A V-VOL with data direct mapping enabled is associated with these pool-VOLs: an external volume for which the data direct mapping attribute is enabled and a pool-VOL with System Area. If you want to create a pool with data direct mapping enabled, define at least one volume to use as the pool-VOL with system area in a pool. For more information about the requirements for the volume used as the pool-VOL with system area, see Prerequisites for creating pools.

By using CCI, you can create an external volume group with data direct mapping enabled and change the pool attribute to the data direct mapping attribute. These operations are not available by using VSP One Block Administrator or VSP block storage REST API.

To use V-VOLs with data direct mapping enabled, you must enable data direct mapping for pool-VOLs, pools, and V-VOLs.

Use the following procedure to use a V-VOL with data direct mapping enabled:

  1. Add a volume from the external storage system (① in the figure) to an external volume group (raidcom add external_grp command).
  2. Create an external volume with data direct mapping enabled (② in the figure) (raidcom add ldev command).

    If the external volume is used as a system pool volume, proceed to step 3. Otherwise, proceed to step 4.

  3. When using the external volume as a system pool volume, if there are no external volumes available to be used as system pool volumes (③ in the figure), create one or more external volumes (raidcom add ldev command).
  4. Create a Dynamic Provisioning pool whose data direct mapping attribute is enabled (hereafter referred to as a pool with data direct mapping enabled) (④ in the figure).

    Use the following procedure to create a pool with data direct mapping enabled:

    1. Create the pool.

      • If step 3 is performed:

        Create the pool by specifying the external volumes created in step 3 as pool-VOLs (raidcom add dp_pool command).

      • If step 3 is not performed:

        Create the pool by specifying a parity group for which no LDEVs have been created (raidcom add dp_pool command).

    2. Change the pool to the data direct mapping attribute (raidcom modify pool command).
    3. Add the external volume with data direct mapping enabled created in step 2 to the pool (raidcom add ldev command).
  5. Create a V-VOL with data direct mapping enabled (⑤ in the figure) (raidcom add ldev command).
  6. Define LU paths (raidcom add lun command).

The following figure shows data direct mapping enabled on the external volume and on the V-VOL.


V-VOLs with direct data mapping

This table shows what kind of external volumes can be added as pool-VOLs.

Operation Data direct mapping attribute of external volumes
Disabled Enabled
Add volumes to a pool with the data direct mapping attribute enabled The volumes can be added. The volumes can be added.
Add volumes to Dynamic Provisioning pools The volumes can be added. The volumes cannot be added.

This table shows what kind of operations can be performed when the data direct mapping attribute of a Dynamic Provisioning pool is enabled or disabled.

Operation Data direct mapping attribute of the pool
Disabled Enabled
Add an LDEV for which the data direct mapping attribute is disabled to the pool The operation can be performed. The operation can be performed.
Add an external volume for which the data direct mapping attribute is enabled to the pool The operation cannot be performed. The operation can be performed.
Set the depletion threshold and the warning threshold The operation can be performed. The operation cannot be performed.
Set subscription The operation can be performed. The operation can be performed.
Protect V-VOLs when I/O fails to Blocked Pool VOL The operation can be performed. The operation can be performed.
Protect V-VOLs when I/O fails to Full Pool The operation can be performed. The operation can be performed.
Performing rebalancing The operation can be performed. The operation can be performed.
Define the used capacity of the pool The sum of the reserved pages capacity and the mapped capacity The sum of the reserved pages capacity and the mapped capacity
Expand pool The operation can be performed. The operation can be performed.

However, the capacity of pool-VOLs with System Area must be reserved in advance.

Shrink pool The operation can be performed. The operation can be performed.

However, if a pool-VOL for which the data direct mapping attribute is enabled is associated with a V-VOL, you cannot shrink the pool.

Delete pool The operation can be performed.

Note: You can delete a pool only when there are no V-VOLs associated with the pool.

The operation can be performed.

Note: You can delete a pool only when there are no V-VOLs associated with the pool.

Create V-VOL You can only create V-VOLs for which the data direct mapping attribute is disabled. You can only create V-VOLs for which the data direct mapping attribute is enabled.

This table shows what kind of operations can be performed when the data direct mapping attribute of a V-VOL is enabled or disabled.

Operation Data direct mapping attribute of the V-VOL
Disabled Enabled
Configure LU paths The operation can be performed. The operation can be performed.
Format LDEVs The operation can be performed. The operation can be performed.
Delete LDEVs The operation can be performed. The operation can be performed.
Expand V-VOLs The operation can be performed. The operation cannot be performed.
Reclaim zero pages The operation can be performed. The operation cannot be performed.
Execute the V-VOL full allocation function The operation can be performed. The operation cannot be performed.