Dell PowerVault ME5 Series Administrator's Guide

Virtual pools and disk groups

The volumes within a virtual pool are allocated virtually (separated into fixed size pages, with each page allocated according to the algorithm within the tiers and disk groups in the pool) and thinly (meaning that they initially exist as an entity, but don't have any physical storage allocated to them). They are also allocated on-demand (as data is written to a page, it is allocated).

You can remove one or more disk groups, but not all, from a virtual pool without losing data if there is enough space available in the remaining disk groups to move the data into. When the last disk group is removed, the pool ceases to exist, and will be deleted from the system automatically. Alternatively, the entire pool can be deleted, which automatically deletes all volumes and disk groups residing on that pool. Deleting a pool that contains data will cause permanent data loss.

If a system has at least two SSDs, each virtual pool can also have a read-cache disk group. Unlike the other disk group types, read-cache disk groups are used internally by the system to improve read performance and do not increase the available capacity of the pool. See Read-cache disk groups for more information.