Dell PowerVault ME4 Series Storage System Administrator’s Guide

Read-cache disk groups

A read-cache disk group is a special type of a virtual disk group that is used to cache virtual pages to improve read performance. Read cache does not add to the overall capacity of the pool to which it has been added. You can add or remove it from the pool without any adverse effect on the volumes and their data for the pool, other than to impact the read-access performance.

If your system uses SSDs, you can create read-cache disk groups for virtual pools if you do not have any virtual disk groups for the pool that are comprised of SSDs. Virtual pools cannot contain both read-cache and a Performance tier.

Only a single read-cache disk group may exist within a pool. Increasing the size of read cache within a pool requires the user to remove the read-cache disk group, and then re-add a larger read-cache disk group. It is possible to have a read-cache disk group that consists of one or two disks with a non-fault tolerant RAID level. For more information on read cache, see About SSD read cache.