Improving file restore performance with caching in disk storage pools

You can use caching for Tivoli® Storage Manager random-access (DISK) storage pools to improve restore performance of files.

When you enable caching for a storage pool, the migration process leaves a cached copy of a file in the storage pool after migrating files to the next storage pool. If your disk storage pool is large enough to hold the backed-up data from one day, then caching is a good method. When you restore files that were recently backed up to a disk storage pool, the benefit of caching is evident. The time that is required to retrieve files is reduced.

Trade-offs for the use of caching include the following performance impacts:

Disk caching can affect backup throughput. When cached files must be deleted to create space for file backups, the deletion operations require database updates.
If you use caching with larger storage pools, they might become fragmented and response time can increase.

Use the DEFINE STGPOOL or UPDATE STGPOOL command with the CACHE=YES parameter to enable caching. If you enable disk storage pool caching, and then suspect that it is affecting performance, try turning off caching. To turn off caching, issue the UPDATE STGPOOL command with CACHE=NO to see whether there is a positive effect.