Tier pool balancing is a function that relocates the physically allocated areas for RAID groups within each sub-pool that makes up a Tier pool so that the usage capacity of each RAID Group becomes even balanced. Therefore, I/O access to the FTV is almost evenly distributed to RAID groups within the FTSP.
Perform a Tier pool balancing when you want to equalize the volumes used by the RAID groups within the FTSP.
Tier pool balancing can be performed regardless of the balancing level. Normally, Tier pool balancing is performed to change the Tier pool balancing level from "Middle" or "Low" to "High".
The balancing level can be confirmed from Balancing:Level that is displayed in the Tier pool overview on the Automated Storage Tiering of the Web Console.
The Tier pool balancing processing can be stopped. The Tier pool balancing can be started/stopped for only one Tier pool within the device.
See
Refer to "Start/Stop Tier Pool Balancing" in the ETERNUS SF Web Console Guide for information on how to start/stop Tier pool balancing.
To perform a Tier pool balancing, the target Tier pool must satisfy all of the following requirements:
Pool Status of the target Tier pool is "Available", "Partially Readying", or "Exposed".
The Tier pool balancing process for the target Tier pool is not running.
Balancing:Status of the target Tier pool is "Stop".
To stop the Tier pool balancing process, target Tier pool must satisfy the following requirement:
Balancing:Status of the target Tier pool is "Active" or "Error".
Point
Even when the business I/Os are occurring on the Tier pool, a Tier pool balancing can be performed on the Tier pool.
The Tier pool balancing level, sub-pool balancing level and balancing progress status can be confirmed with the Web Console. Refer to "4.3 Confirmation of Configuration Details of Tier Pool" for details.
Note
Perform a Tier pool balancing after stopping Automated Storage Tiering for the target Tier pool. Refer to "Start/Stop Automated Storage Tiering for Tier Pool" in the ETERNUS SF Web Console Guide for information on how to stop Automated Storage Tiering of a Tier pool.
Tier pool balancing prioritizes FTVs with a low balancing level within the Tier pool and a maximum of 32 FTVs can be balanced at a time. For this reason, if there are many FTVs, there may be times when the balancing level does not become "High" even if a Tier pool balancing is performed. To make the balancing level "High", reperform a Tier pool balancing.
If the balancing status is "Error", stop the Tier pool balancing process for that Tier pool.
Even if a Tier pool balancing is performed, the sub-pool that was physically allocated with the FTV is not changed.
Tier pool balancing cannot be performed if any of the following conditions are satisfied:
Operating Status of the target Tier pool is "Start".
An FTV does not exist in the target Tier pool.
A Tier pool that is performing a Tier pool balancing exists within the storage device.
The maximum number of volumes is registered on storage device.
The number of sessions for a Thin Provisioning Volume balancing and RAID Migration is a combined 32 processes executing at the same time in the storage device.
The migration capacity for a Thin Provisioning Volume balancing and RAID Migration is a combined 128 TB process executing at the same time in the storage device.
A RAID group diagnosis is being executed on the storage device.
A disk diagnosis is being executed on the storage device.
The capacity is being optimized for all FTVs to be balanced that exist on the target Tier pool.
ODX is being executed for all FTVs to be balanced that exist on the target Tier pool.
An FTV to be balanced that exists on the target Tier pool is using the RAID group that is being deleted.
The Tier pool balancing process cannot be stopped for the following cases:
The Tier pool performing the Tier pool balancing does not exist.
The Tier pool stopping the Tier pool balancing due to an error does not exist.
The Tier pool balancing process for the target Tier pool is completed.
When creating, deleting, or configuring the FTV, the balancing level is not updated. Execute a status update of Automated Storage Tiering to update the balancing level.
FTVs that satisfy any of the following conditions are not targets for the balancing process:
FTVs with a total capacity of 20 GB or less
FTVs with a used capacity of 10 GB or less
