IBM Tivoli Storage Manager, Version 7.1

Controlling the number of mount points for a device class during simultaneous-write operations

If the number of sequential-access volumes that must be mounted for a simultaneous-write operation exceeds the maximum number of mount points specified for a device class, the server is not able to acquire the mount points and the operation fails.

About this task

To specify the maximum number of sequential-access volumes that can be simultaneously mounted, use the MOUNTLIMIT parameter in the device class definition.

If the simultaneous-write operation involves an active-data pool, the IBM® Tivoli® Storage Manager server tries to remove the active-data pools that use this device class until enough mount points can be acquired. The transaction fails, and the client tries the operation again. If sufficient mount points can be acquired when the operation is tried again, the data is written into the primary storage pool, any remaining active-data pools, and any copy storage pools, if they exist.

If the operation involves a copy storage pool, the value of the COPYCONTINUE parameter in the storage pool definition determines whether the client tries the operation again:
  • If the value of the COPYCONTINUE parameter is NO, the client does not try the operation again.
  • If the value of the COPYCONTINUE parameter is YES, the server tries to remove the copy storage pools that use this device class until enough mount points can be acquired. The transaction fails, and the client tries the operation again. If sufficient mount points can be acquired when the operation is tried again, the data is written into the primary storage pool, any remaining copy storage pools, and any active-data pools, if they exist.
Restrictions:
  • The setting of the COPYCONTINUE parameter does not affect active-data pools. If a write failure occurs for any of active-data pools, the server stops writing to the failing active-data pool for the remainder of the session, but continues storing files into the primary pool and any remaining active-data pools and copy storage pools. The active-data pool list is active only for the life of the session and applies to all the primary storage pools in a particular storage pool hierarchy.
  • The setting of the COPYCONTINUE parameter does not affect the simultaneous-write function during server import. If data is being written simultaneously and a write failure occurs to the primary storage pool or any copy storage pool, the server import process fails.
  • The setting of the COPYCONTINUE parameter does not affect the simultaneous-write function during migration. If data is being written simultaneously and a write failure occurs to any copy storage pool or active-data pool, the failing storage pool is removed and the data migration process continues. Write failures to the primary storage pool cause the migration process to fail.


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