Symptoms

Avamar 6.0: CBT Backups are taking a long time to complete and completing with exceptions. CBT is enabled on both the Virtual Machine (VM) and the dataset. Reviewing the avvcbimage log reveals that the changed block tracking was enabled, but the base backup was not available: 2012-08-22 20:19:08 avvcbimage Info <11986>: Changed block tracking is engaged for this VM 2012-08-22 20:19:08 avvcbimage Info <11988>: A reference to a valid prior backup is not available so this will be a full level zero backup. The avtar.log has the following error: 2012-08-22 20:19:23 avtar Error <7922>: Invalid expires input value. The avtar.log also reveals that the backup had already been expired when the backup completed: 2012-08-23 10:50:15 avtar Info <5156>: Backup #10 timestamp 2012-08-23 10:45:31, 12 files, 190.0 GB (12 files, 323.0 MB, 0.17% new) 2012-08-23 10:50:15 avtar Info <7539>: Label "Daily-BackupOnceToday-1345633352030", scheduled to expire 08/22/12, daily backup, backup type: level0_full

Cause

The cause was a misconfiguration of the advanced retention settings, where the value for "Keep dailies for" was set to "0" by mistake. A value of "0" means that the daily backups do not have a retention time, forcing them to expire at the beginning of each backup.

Resolution

To ensure that the daily backups are not deleted immediately after completion, perform one of the following to correct the retention issue: Keep using the advanced retention Set the value for "Keep dailies for" to the number of days that the daily backup must be retained for. Use the basic retention instead, where the retention time is the same for all retention flags (daily, weekly, monthly, yearly, none) Ensure that the number of days that the backups must be retained for is sufficient. CBT backups should start to work after one of the above is set. Note: Initial (level 0) backups will take longer, but the subsequent backups should run faster.

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