About scratch volume pools
The scratch pool is an optional pool that contains the media that NetBackup can allocate to other pools as needed. If you configure a scratch pool, NetBackup moves volumes from that scratch pool to other pools that do not have volumes available.
Only one scratch pool is allowed. You cannot add a scratch pool if one exists.
You cannot change the NetBackup or DataStore pools to be scratch volume pools.
If you create a scratch pool, be aware of the following conditions:
If the scratch pool contains assigned volumes, these volumes remain in the scratch pool.
NetBackup does not move assigned volumes to other pools as it does with unassigned volumes.
NetBackup does not assign volumes while they are in a scratch pool.
For example if a NetBackup policy or schedule specifies the scratch pool, all requests for those volumes are denied.
NetBackup returns expired media to the scratch volume pool automatically (media that is returned must have been originally in the same scratch pool).
To use NetBackup to manage the allocation of volumes to volume pools, do the following:
Create volume pools as required, but do not add any volumes to the pools.
Define a scratch pool and add all of the volumes to it. NetBackup moves volumes to the other pools as volumes are needed.
See About NetBackup volume pools.