262 IBM Tivoli Storage Manager Versions 5.4 and 5.5 Technical Guide
The new migration method provided for the FILE device storage pool allows you to set your
migration thresholds considering overall use of your disk resources instead of the number of
volumes being used.
20.2 Concurrent read access for sequential disk
Before Tivoli Storage Manager V5.5, a client session or server process had to wait for a FILE
volume if the volume was in use by another session or process. At V5.5, multiple client
sessions and server processes can access FILE volumes concurrently, which reduces or
eliminates wait times for read access to FILE volumes.
No configuration changes are required to take advantage of the concurrent read access,
however we recommend increasing the MAXNUMMP for nodes accessing FILE volumes.
This allows for greater concurrency for node read operations, for example, when doing
multi-threaded restores. In addition, make sure the MOUNTLIMIT parameter for the device
class provides enough mount points for concurrent access.
Concurrent read access is not limited to client read operations but is also available for server
internal operations that request volume read access, such as BACKUP STORAGEPOOL,
AUDIT VOLUME, and others.
We use the following simple scenario to demonstrate defining NODE1 to NODE4, all
belonging to a domain where the backup destination points to a FILE device storage pool,
CPOOL. The mount limit for the device class is set to 10.