SANREFRESHTIME option's default, minimum, maximum, and suggested values.

Answer

The SANREFRESHTIME Tivoli Storage Manager Server option was initially introduced in version 5.3/5.4 to allow the Server to cache SANDISCOVERY information for a specified period of time. After this period of time has expired, SANDISCOVERY can run again (when required) to update the SAN device mapping information.

Caching this information can be useful on busy, but stable, SAN systems since SAN discovery does require a certain amount of overhead to run, which can cause performance degradation. More information about this option can be found in the Tivoli Storage Manager Admin Reference Guide.

The default value for this option is 0 seconds (which means the cache is disabled).
The minimum value for this option is also 0 seconds.
The maximum value for this option is 2,147,483,647 seconds.

For stable SAN environments, a suggested starting value for this option is 24 hours, or 86,400 seconds. This will reduce the frequency that SAN discovery runs, and reduce its related overhead. For unstable SAN environments, a lower value is better, however, disabling the cache with a SANREFRESHTIME of 0 is preferential - understanding that this can increase SANDISCOVERY overhead and induce performance degradation in SANDISCOVERY is running frequently.

Note that the QUERY SAN admin command will refresh SAN information regardless of the SANREFRESHTIME setting.

This option is applicable on both Servers and Storage Agents.