For an introduction to Veeam Backup & Replication’s options for rotated media, consult the user guide. The following notes assume the option for rotated media is enabled in the repository advanced settings.
There are three options:
Backup jobs will always create active full backups immediately after disks are rotated. This option requires that each storage medium has sufficient disk space for at least two full backup files.
With backup copy jobs, when a new disk is detected, the job will only create a full backup if there are no valid backups on the disk for that job. If an existing backup set is detected, the backup copy job will create an incremental backup file that contains the difference between the current restore point and the most recent previous restore point on that disk. As a result, if disks are re-used frequently, the incremental backup files will be similar in size to increments on non-rotated media; if a disk contains very old restore points, the first new incremental backup copy may be almost as large as a full backup.
With both job types, Veeam Backup & Replication tracks restore points stored on all disks that have been used with the job. If outdated restore points are stored on the current disk, they are only deleted at the end of the current job session.
For example, consider a job that creates two restore points per day, with disks swapped once per day, a total of three disks, and retention policy set to 6 restore points.
If a disk does not contain enough space for a new backup file, the job will fail instead of deleting old files. This can be avoided by deleting old files as soon as the disks are swapped. This can be done manually, via pre-job script, or with the registry setting described below.
By default, repositories configured for rotated media do not delete any backup files when disks are swapped. If a disk containing a previous backup is to be re-used, but lacks sufficient available space for new backup files, the old files must be deleted manually, or by a pre-job script.
Retention policy is enforced, but only on the current backup chain. For example, consider a backup copy job that creates restore points every hour, with disks swapped once per day, and retention policy set to 6 restore points. Once there are 7 restore points on the current disk (a full backup file and 6 incremental backup files), the oldest increment is merged with the full backup file so that there are 6 restore points on disk. The disk is swapped out for a new one, and the process repeats. When the first disk is re-used, the 6 backup files still on the disk are ignored. A new full backup file is created, and a new chain of incremental files. At the end of the day, there are 12 restore points on disk, with only the most recent 6 visible in the Veeam Backup & Replication console.
An alternative behavior is available as a registry setting (below).
When this registry setting is enabled (set to 3 or 5), any repository, regardless of rotated media setting, will maintain retention normally until the job detects that previously-available files are missing.
Create this value on the Veeam Backup and Replication server:
Location: HKLM\SOFTWARE\Veeam\Veeam Backup and Replication\
Type: DWORD (32 bit)
Value: (seee below)
*Starting with Veeam Backup & Replication v9 all registry values are checked every 15 minutes, so a reboot will not be required but the service must be given time to rescan the registry and find the new setting.
Backup repositories with rotated drives have the following limitations: