This query is useful for observing when recall mounts occur and to see the impact of virtual volume recalls on workload throughput. When a requested volume is in cache, the time to satisfy the mount is less than 1 second. A cache miss means that the requesting workload must wait for the virtual volume to be recalled from the physical cartridges backing the tape server and copied to cache before the mount request can be satisfied. While recalls cannot be eliminated, minimize them. If excessive recalls are observed, the storage administrator can determine the characteristics of the volumes being recalled and make configuration changes to try to increase the chance that virtual volumes are in cache when requested.
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