Acronis Backup for Linux Server - User Guide - Manual (Page 72)

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4.5.4 Retention rules for the Custom scheme
In the Retention Rules window, you can select how long to store backups in the location and
whether to move or delete them afterward.
The rules will be applied to all the backups taken on the specific machine and put in this specific
location by this specific backup plan. In Acronis Backup, such set of backups is called an archive.
To set up retention rules for backups:
1. Specify one of the following (options (a) and (b) are mutually exclusive):
a. Backups older than... and/or Archive size greater than....
A backup will be stored until the specified condition (or both of the conditions) are met.
Example:
Backups older than 5 days
Archive size greater than 100 GB
With these settings, a backup will be stored until it is older than five days and the size of
the archive containing it exceeds 100 GB.
b. Number of backups in the archive exceeds...
If the number of backups exceeds the specified value, one or more of the oldest backups
will be moved or deleted. The minimal setting is 1.
2. Select whether to delete the backups or to move them to another location if the specified
conditions are met.
You will be able to specify the location where to move the backups and set up retention rules for
that location after you click OK.
Deleting the last backup in the archive
The retention rules are effective if the archive contains more than one backup. This means that the
last backup in the archive will be kept, even if a retention rule violation is detected. Please do not try
to delete the only backup you have by applying the retention rules before backup. This will not work.
Use the alternative setting Clean up archive > When there is insufficient space while backing up (p.
46) if you accept the risk of losing the last backup.
Deleting or moving backups with dependencies
To access this setting, click Show advanced settings in the Retention Rules window.
Retention rules presume deleting or moving some backups while retaining the others. What if the
archive contains incremental and differential backups that depend on each other and on the full
backups they are based on? You cannot, say, delete an outdated full backup and keep its incremental
“children”.
When deletion or movement of a backup affects other backups, one of the following rules is applied:

Retain the backup until all dependent backups become subject to deletion (movement)
The outdated backup (marked with the icon) will be kept until all backups that depend on it
also become outdated. Then, all the chain will be deleted at once during the regular cleanup. If
you chose moving outdated backups to the next location, the backup will be copied there
without delay. Only its deletion from the current location is postponed.
This mode helps to avoid the potentially time-consuming consolidation but requires extra space
for storing backups whose deletion is postponed. The archive size and/or the backup age or
number can exceed the values you specify.