Revisions are versions of a file at a specific point in time. You configure revision settings when you create a backup selection. When a file is changed and backed up, DLO stores a new revision. DLO stores and maintains a specific number of revisions for all files in a backup selection. Because backup selections are configured separately, the number of revisions that are retained in each backup selection can vary. When the number of revisions is exceeded, DLO removes the oldest revision.
You can limit the number of revisions that are retained in a given period of time. If you back up a document frequently while you work on it, all of your revisions could potentially be a few minutes apart. By specifying that you want to retain only two revisions every 24 hours, at least 120 minutes apart, you can retain older revisions for a longer period of time. While some intermediate versions are not retained, it does support situations in which returning to an older revision is needed.
Another consideration in determining the number of revisions to retain is the amount of storage space that is required to store the data. The amount of space that is required for backups can be estimated by multiplying the number of revisions that are retained by the amount of data protected.
Although compression can improve the space utilization, it varies significantly with file type and other factors. Typical compression ratios are approximately 2:1, so in the example, the maximum disk space usage might be reduced to approximately 15 MB.