Challenge
This article is intended to document how Backup Copy’s retention is enforced.Solution
──────────────────────────────────────────────────────────Backup Copy Retention – Simple Retention Policy
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To maintain the desired number of restore points, Veeam Backup & Replication uses the following rotation scheme:
1. At the first synchronization interval, Veeam Backup & Replication copies the first restore point — full backup — to the target backup repository.
2. At every next synchronization interval, Veeam Backup & Replication adds a new restore point — incremental backup — to the chain on the target backup repository. This happens until the number of restore points in the backup chain reaches the number specified in the retention policy settings.
3. After the new restore point is added, the allowed number of restore point is exceeded. Veeam Backup & Replication transforms the backup chain to make room for the most recent restore point.
The backup chain transformation is performed in the following way:
1. Veeam Backup & Replication re-builds the full backup file to include changes of the incremental backup following the full backup. More specifically, it injects data blocks from the first incremental backup in the chain into the full backup. This way, a full backup ‘moves’ one step forward in the backup chain.
2. The first incremental backup is removed from the chain as redundant: its data has already been injected into the full backup and so the full backup file contains the same data as this incremental restore point.
Within this animation the lettered squares represent blocks on a disk.
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Backup Copy Retention – “GFS” Retention Policy
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GFS restore points are not created in a separate task. Veeam Backup & Replication re-uses a full backup created in the regular backup cycle and propagates it to the appropriate tier.
For an in-depth explanation of this please see:
https://helpcenter.veeam.com/backup/vsphere/backup_copy_gfs_weekly_cycle.html
For example below the following settings are used:
Within this animation the lettered squares represent blocks on a disk.