Pool-VOLs are grouped together to create a pool. When a new pool is created, the available pool-VOLs are selected in the Select Pool VOLs window and added to the Selected Pool Volumes table. Every pool must have a pool-VOL with System Area.

When adding a volume to the pool for which Multi-Tier Pool is enabled, note the following:

• Up to three different drives types/RPM are allowed between all the pool-VOLs to be added.
• Volumes to be added to the same pool must have the same RAID level across all the same drive type/RPM pool-VOLs.

  For example, you cannot add a volume whose drive type/RPM is SAS/15k and whose RAID level is 5 (3D+1P) when a volume whose drive type/RPM is also SAS/15k but whose RAID level is 5 (7D+1P) is already in the pool.

• Up to three values are allowed for Drive Type/RPM for the volume.

If you increase the pool capacity by adding a pool-VOL, a portion of the existing data in the pool automatically migrates from an older pool-VOL to the newly added pool-VOL, balancing the usage levels of all the pool-VOLs. If you do not want to automate balancing of the usage levels of pool-VOLs, call customer support for assistance.

Dynamic Provisioning does not automatically balance the usage levels among pool-VOLs if the cache memory is not redundant or if the pool usage reaches up to the threshold.

The pool-VOLs contained in a pool can be added or deleted. Removing a pool-VOL does not delete the pool or any related DP-VOLs. You must delete all DP-VOLs related to the pool before the pool can be deleted. When the pool is deleted, all data in the pool is also deleted.