Start Balancing Thin Provisioning Volume

Overview

This function relocates the physical allocating area of the Thin Provisioning Volume (TPV) to equalize the used capacity of TPVs among the RAID groups that configure the Thin Provisioning Pool (TPP).

When multiple TPVs in the same TPP are accessed, the Thin Provisioning function allocates physical area by using the RAID groups of the TPP one by one in the access order. Therefore the physical area of TPVs may be unequally allocated among the RAID groups. This phenomenon also occurs when expanding the capacity of a TPP. In this case, the physical area is allocated unevenly among the newly added and existing RAID groups. This function is to solve the unequal allocation among RAID groups, and balance the physical allocating area in each RAID group. I/O load is dispersed among the RAID groups in the TPP and access performance may be improved.

Requirements for a TPV to be balanced

  • The volume type is "TPV"

  • The volume status is "Available"

  • RAID migration is not being performed (the target volume is not used as a migration source or a migration destination)

  • An Advanced Copy is not being performed (the target volume is not being used as a copy source or a copy destination)

  • A Remote Advanced Copy is not being performed (the target volume is not being used as a copy source or a copy destination)

  • ODX is not being performed

  • TPV balancing is not being performed

  • Capacity optimization for TPV is not being performed

  • Not used as Deduplication/Compression Volumes

  • Not used as Data Container Volumes

Requirements for a TPP in which the target TPV is registered

  • The volume status is "Available"

  • The free space in the TPP is the same or larger than the capacity of the TPV that is to be balanced

  • When the allocation mode for the TPV is "Thick", the free physical capacity for allocating the whole area exists

Caution
  • The TPV balancing cannot be performed in the following conditions:

    • The maximum number of volumes are already registered in the storage system

    • When the total number of TPV balancing sessions, RAID migration sessions, and FTV balancing sessions (*1) that are running in the storage system at the same time is 32

    • When the total capacity for the TPV balancing sessions, the RAID migration sessions, and the FTV balancing sessions (*1) that are running in the storage system is 128 TB

    • The TPP capacity that can be registered in the storage system is insufficient

    • The sum of the total logical capacity for all the volumes in the pool and the capacity of the work volume exceeds the maximum pool capacity (*2)

    *1  :  When an FTRP balancing session is started, FTV balancing starts in the FTSPs. Refer to the [Start Balancing Flexible Tier Pool] function for details.
    *2  :  When a TPV balancing is performed, an area for a work volume (or the migration destination TPV with the same capacity as the migration source) is temporarily acquired in the TPP to which the target TPV belongs. Therefore, if the sum of the work volume capacity and the total logical capacity of the volumes (TPVs and FTVs) in all the existing pools (TPPs and FTRPs) exceeds the maximum pool capacity, a work volume cannot be created, and this function becomes unavailable.

  • This function balances the physical allocating area of the TPV among RAID groups of the TPP to which the TPV belongs. It is not able to balance TPV by RAID migration of the TPV to other TPPs.

Note

  • TPV balancing can be performed during the work I/O.

  • The progress of a balancing TPV can be checked in the [Balancing TPV] screen.

  • The allocation method for the TPV can be checked in the [Volume] screen. Refer to the [Volume (Basic Information)] function for details.

User Privileges

Availability of Executions in the Default Role

Default role Availability of executions
Monitor  
Admin
StorageAdmin
AccountAdmin  
SecurityAdmin  
Maintainer

Refer to "User Roles and Policies" for details on the policies and roles.

Operating Procedures

  1. Select the TPV to be balanced and click [Start Balancing] in [Action].

    → A confirmation screen appears.

    Caution

    • [Start Balancing] cannot be clicked if NAS expanded system volumes are selected.

  2. Click the [OK] button.

    → TPV balancing starts.

  3. Click the [Done] button to return to the [Balancing Thin Provisioning Volume] screen.