If multiple parity groups that contain LDEVs used as pool-VOLs exist, rebalancing can improve biased usage rates in parity groups.
Rebalancing is performed as if each parity group were a single pool-VOL. After rebalancing, the usage rates of LDEVs in a parity group may not be balanced, but the usage rate in the entire pool is balanced.
The usage level among parity groups is automatically rebalanced when expanding or shrinking pool capacity operations are in progress.
If you expand the pool capacity, Dynamic Provisioning moves data to the added space on a per-page basis. When the data is moved, the usage rate among parity groups of the pool-VOLs is rebalanced.
Host I/O performance may decrease when data is moved. If you do not want to have the usage level of parity groups automatically balanced, call customer support.
You can see the rebalancing progress of the usage level among parity groups in the View Pool Management Status window in HDvM - SN. In CCI, you can use the raidcom get pool -key command to see if the usage levels among parity groups are rebalanced. Dynamic Provisioning automatically stops balancing the usage levels among parity groups if the cache memory is not redundant or the pool usage rate reaches up to the threshold.