Relica lets you set retention periods on destinations so that old data gets deleted on a regular basis. This helps you keep the size of your backup under control.
Retention periods are optional, and may be adjusted on the Edit Destination page for any of your backup destinations. By default, the retention period for a destination is unlimited, meaning never delete any data from the backup.
A retention period specifies the length of time to keep all data, even after it has been moved or deleted from the source (or "origin"). If a retention period is set, then data that was backed up at least that long ago and which is no longer present on your hard drive (or whatever the source is) will be removed from the backup.
Retention periods are relative to the time of the last snapshot (or "most recent backup") at a destination. This ensures that even if your computer "goes dark" (is disconnected or unable to run backups for some reason) for a long period of time, your backup still retains all your files across the entire duration you specify: in other words, backup destinations will not start losing data simply because your computer stopped making new backups.
The span of time during which you can restore a file after its deletion is called a retention window.
Retention windows are created as Relica runs in the background on your computers. Relica enforces the retention period for a destination from any of the computers on your account which can access it. This happens automatically on a regular basis. Relica will scan your destinations for old data according to your retention preferences and prune (delete) the data which has since been deleted from your computer.
If none of your computers with access to a destination are able to perform the prune operation, the retention period will not be enforced until Relica has a chance to run its maintenance operations.
Retention periods are not exact: depending on computer connectivity, the timing of regular automatic maintenance, etc, retention periods may be a day or a few days longer than what you specify; it's a ballpark range.
For example, suppose your computer makes daily backups to a destination with a retention period of 365 days (1 year). Then after 1 year, the computer goes into storage and stops making backups because it is not turned on. But 6 months after the year, you realize you need an important file from its very first day of operation—a file that was only needed that one day and was deleted the day after.
Fortunately, Relica still has the very first backup from that very first day, because the retention window doesn't slide until a new backup is made. Since the last backup was made within the retention window of the first, Relica still has that file and you can restore it.
Relica Cloud Retention
As with other destinations, you can set a retention period for your backups in the Relica Cloud. If you set one, the minimum retention is 90 days. Other destinations have no restrictions on the retention period.
Changing the Retention Period
When you change the retention period, the new period is enforced starting at the next maintenance operation.
If you lengthen the period, more data will begin to accumulate in your destination over time as you perform more backups, since less old data will be deleted for a little while.
If you shorten the period, more data will be deleted on the next maintenance operation in order to bring the destination into conformity with your updated preferences.
Changing the retention period does not necessarily run maintenance right away; the usual maintenance ticker continues in the background, and it will apply your settings at the next run.
Relica performs maintenance on your destinations on a regular basis; this routine runs automatically and in the background—no action is required by you (except to leave your computer on sometimes). A destination cannot be maintained while a backup or restore is actively happening. Restore operations will preempt maintenance operations, interrupting them until the next cycle, so that restores can happen immediately.
The specific maintenance required to enforce the retention period is also not performed while any backup to that destination has started but is incomplete, even if the backup is not actively happening at that moment. This is because large backups with long uploads may be interrupted and resumed later, and if pruning maintenance was performed, the data that was uploaded but is not yet part of a complete snapshot would be deleted, forcing the backup to start over. Note that if you deliberately cancel a backup operation, the backup will be considered "complete" even though it did not finish (thus allowing maintenance to happen). This is to give you more control over your backups. Backups that are interrupted in any other way will still be considered "incomplete" until they finish successfully or stop with an error.
This is not a problem—Relica is designed to handle it—but it means that maintenance takes second priority to backups and restores, and the first maintenance operations on a large backup might not have a window to take place until after the initial backup completes.
We want to emphasize that the retention period setting is the primary way of deleting data in a backup to keep the size of a backup under control. Setting it to a low value, like 1 day, doesn't mean all backups older than 1 day will be deleted: only data that is not still present on your computer (data that has been moved or deleted) will be deleted after it has been stored for 1 day in the backup. That is how a retention period works; so even low values are not dangerously destructive—unless, of course, the original files get deleted or moved out of the backup set. Use caution when setting low values for the retention period.
We recommend most customers set an unlimited retention period on their destinations, but it depends on how valuable or important your files are and how much space you have to store backups. If you have limited space or a lot of data and a very limited budget, set a lower period. If you value being able to restore any lost files in the distant future, set a high or unlimited period.