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How the Purge Policy and a DB Pruning Job Works for Synthetic Full Backup

Tape data, ASDB information, and the Catalog file of sessions pending synthesization cannot be purged by the job engine and a DB pruning job. It will use the following algorithm to get a minimum data retention time for the session that is pending synthesization:

MAX( MIN( Synthetic Cycle Time * 2, Real Full Cycle Time ), Session Retain Time in Purge Policy )

This ensures there is always at least one full backup (regardless if it is a real full backup or synthetic full backup) session and all subsequent incremental sessions. Because Arcserve Backup will not prune catalog files for these sessions, the CATALOG.DB folder may use disk space, the size of which depends on your backup sources and purge policy.

Arcserve Backup treats one full backup (regardless if it is a real full backup or synthetic full backup) session and all subsequent incremental sessions as a unique session set that will be used for the next synthetic job. Therefore, the full backup session and all subsequent incremental sessions will have the same purge policy even if you have set a different purge policy for full backups and incremental backups. Arcserve Backup calculates the purge time for the full session only and applies the same purge time for all subsequent incremental sessions.

You can determine the purge time for synthetic related sessions by viewing the master job log in the activity log.