Revisions are versions of a file at a specific point in time. 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 each backup selection is configured separately, the number of revisions that are retained can vary for different backup selections.

When the number of revisions is exceeded, DLO removes the oldest revision. It maintains only the specified number of revisions in the desktop and network user data folders.

You can limit the number of revisions DLO retains in a given period of time. If you back up a document frequently, all of your revisions could potentially be a few minutes apart. By specifying that you want to retain only 2 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.

For example, if you retain three revisions of each file and have 10 MB to back up, approximately 30 MB of disk space is required.

Although compression can improve the space utilization, it varies significantly with file type and other factors.

DLO protects all of the alternate streams for a file, including security streams. If a new version of a file contains only alternate stream data modifications, the new version replaces the old version without impacting the revision count.