Media availability failures
In tape-based backup solutions, failures can occur if no suitable tape media is available for use by a backup job. With NetBackup, risk of such failures can be reduced through global scratch pools and media sharing.
Table: NetBackup protection against media availability failures discusses the methods of protection against media availability failures.
Table: NetBackup protection against media availability failures
Protection method | Description |
|---|---|
Global scratch pools | For all the backup jobs and duplication jobs that are written to tapes, use the tapes that are in a specific media pool with the same retention criteria as the backed up data. If no suitable tapes are available, the backup fails. A global scratch pool is a NetBackup media pool that holds unassigned tapes that can be automatically re-assigned to a specific media pool on demand. For instance, a backup or a duplication job runs and no suitable tapes are available in the media pool specified by the job. Then an unassigned tape is transferred from the global scratch pool to the specified media pool and is used for the backup job. When this tape expires, it is automatically returned to the global scratch pool for re-use. Using a global scratch pool ensures that all unassigned tapes are available for use by any backup job, irrespective of the media pool specified by the job. |
Media sharing | Media sharing allows multiple media servers to use partially full tapes until they are full. It ensures the most efficient use of tape. Only one media server at a time can write to a tape. When that tape is not in use, a different media server that requires a tape from that media pool can use it. To enable media sharing, set the Volume Pool properties to use the Maximum number of partially full media property. This property restricts the number of partially full tapes in a media pool. Until all tapes are full, empty tapes cannot be assigned to the pool. Until one tape is full, another empty tape cannot be assigned to the pool. |