CrashPlan tracks multiple versions of each file as it backs up changes over time. Version snapshots can be restored from an archive to revert to the file's previous state. This tutorial includes instructions for changing your version retention settings.
In CrashPlan, version retention means keeping more of the recent versions of your backed up files and less of the older ones. Subscribers of CrashPlan for Home have the option to change the default version settings, which includes the ability to keep all versions of all files forever.
Specifying the versions to retain involves:
CrashPlan backs up new changes to files as often as your Backup Frequency settings allow. CrashPlan watches the filesystem in real-time (unless that feature is turned off), and when a file changes it schedules the next backup of that file based on the frequency settings (i.e. if the backup frequency is set to the default 15 minutes, once a file changes CrashPlan will schedule a backup to happen 15 minutes later).
CrashPlan retains the newest version in several intervals:
CrashPlan selectively prunes out older file versions during the regular archive maintenance process. This decreases the amount of data CrashPlan tracks as the archive grows and decreases memory usage in the CrashPlan app (i.e. two months from now, you may not need to restore a file from 8:45AM when the hourly snapshot will do).
You can take full control over how aggressive the pruning process is, so if you want to keep every possible version of every change backed up, you can!
If you delete a file from your computer that was previously backed-up, CrashPlan keeps it in the archive for as long as indicated in the deleted files retention setting. CrashPlan never removes deleted files from the archive by default.
You can change your version retention settings from Settings > Backup using the steps below.
This feature is available to subscribers of CrashPlan for Home.
The following example displays the default retention settings for each interval:
In this example, CrashPlan retains the most recent file backed up each day in the last week, plus the most recent file backed up each day for the last 90 ninety days (that is, in addition to last weeks' files), plus one version per week for the last year, plus one version per month for the years prior to last year.
In another example, if you choose to retain two versions per week CrashPlan will retain the most recent version backed up at the end of the week, plus the most recent version backed up 3 and a half days earlier, in essence splitting the difference.