Regulating restore sessions

When you request a restore, the default is to use a maximum of one session.

Additional restore sessions are based on:
  • resourceutilization value
  • how many tapes on which the requested data is stored
  • how many tape drives are available
  • the maximum number of mount points that are allowed for the node
Note:
  1. If all of the files are on disk, only one session is used. There is no multi-session for a pure disk storage pool restore. However, if you are performing a restore in which the files are on 4 tapes and others are on disk, you could use up to 5 sessions during the restore.
  2. The IBM Spectrum Protect™ server can set the maximum number of mount points a node can use on the server by using the MAXNUMMP parameter. If the resourceutilization option value exceeds the value of the MAXNUMMP on the server for a node, the backup can fail with an Unknown System Error message.
  3. You can get a multi-session restore from your single restore command, and from a single volume on the server, if that volume is device class FILE.

For example, if the data you want to restore is on 5 different tape volumes, the maximum number of mount points is 5 for your node, and resourceutilization is set to 3, then 3 sessions are used for the restore. If you increase the resourceutilization setting to 5, then 5 sessions are used for the restore. There is a 1 to 1 relationship between the number of restore sessions that are allowed and the resourceutilization setting. Multiple restore sessions are only allowed for no-query restore operations.