Chapter 7 Thin Provisioning Pool Management
7.2 Functions in the Action Area for Thin Provisioning
ETERNUS Web GUI User’s Guide
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7.2.12 Start Balancing Flexible Tier Pool
This function starts Flexible Tier Pool (FTRP) balancing sessions.
The FTRP balancing function equalizes unevenly allocated physical area in the Flexible Tier Sub Pools (FTSPs)
that configure an FTRP. By using this function, the physical allocated areas are reallocated equally among the
RAID groups in the FTSPs. The I/O access to the FTV is distributed almost equally to the RAID groups in the
FTSP.
Requirements for an FTRP to be balanced
• The status of the FTRP is " Available", " Partially Readying", or " Exposed"
• Balancing of the selected FTRP is not being performed
• Free space, which can be used for balancing, exists in the FTSPs in the target FTRP
• Even after the FTRP balancing session is performed, the physical allocation between the FTVs and the
FTSPs does not change.
• The FTRP balancing function extracts up to 32 balanceable FTVs (*1) that have a low balancing level from
the selected FTRP and performs balancing sessions in the FTSPs. Note that FTVs are not extracted as
balancing targets in certain conditions. For example, FTVs with a high balancing level, FTVs that are
undergoing RAID migration, or FTVs that are undergoing Zero Reclamation.
*1: Up to 32 sessions, which include FTV balancing sessions, TPV balancing sessions, and RAID migration sessions,
can be performed at the same time. An FTRP balancing session is performed in each FTRP. Note that the number
of FTV balancing sessions that are performed at the same time cannot be specified.
• Balancing of FTVs in the following conditions is not available:
- FTVs which capacity is less than 20GB
- FTVs which used capacity is less than 10GB
The FTV capacity can be checked in the [Flexible Tier Pool Detail (Volume)] screen. Refer to "7.1.9 Flexible
Tier Pool Detail (Volume)" (page 215) for details.
• FTRP balancing cannot be started in the following conditions:
- When the Thin Provisioning license is not registered
- When the Flexible Tier function mode is disabled
- When the maximum number of volumes is already registered in the ETERNUS DX Disk storage system
- When the total number of TPV balancing processes and RAID migrations that are running in the
ETERNUS DX Disk storage system is 32
- When the total capacity for the TPV balancing processes and the RAID migrations that are running in
the ETERNUS DX Disk storage system is 128TB
- When the RAID group diagnosis is being performed in the ETERNUS DX Disk storage system
- When the disk diagnosis is being performed in the ETERNUS DX Disk storage system
- When Zero Reclamation is being performed for all of the balancing target FTVs in the FTRP
• When FTRP balancing is performed, the used FTRP capacity may temporarily exceed the threshold. If the
used capacity exceeds the threshold, " Attention" or " Warning" is displayed in the "Used Status"
field for the FTRP. The usage of the FTRPs is displayed in the [Flexible Tier Pool] screen. Refer to "7.1.5
Flexible Tier Pool (Basic Information)" (page 207) for details.