ReverseDelta is technology developed by Altaro Software that enables Altaro Hyper-V Backup to only save the changes between each version of a changed file, rather than backing up the whole file every time it changes.

This means that keeping multiple backup versions will require less space on your backup drive.

What distinguishes ReverseDelta from other delta technologies?

At Altaro we listened to what users felt was the main concern about delta files. The problem is that in the event of heavy data loss, the version of a file you are most likely to need is the latest one.

Most backup solutions keep the first backup and save the changes (deltas) since that first backup, which, after a few weeks or months can become much more complex to restore.

Many users are apprehensive if this version may need to be rebuilt from an older version and one or more delta files.

With ReverseDelta, the latest version of a file is always made available in its entirety and not as a delta file. This means that if you require the latest version of a file, it is possible to access it directly from your backup drive without having to rebuild it from delta files. The delta files are only used if you want to build a previous version of the file, building one delta file at a time for each version as you travel back in time in the reverse direction.

ReverseDelta is recommended for large files that change often, such as Outlook PST files or database backup files.

The following diagram shows a more visual representation of the whole process. The diagram represents a simple example of a file that is backed up four times (the first time, followed by 3 different versions of the file), and shows the way Reverse Delta optimizes the storage space on the drive.

Steps 1,2 and 3 show the initial stages involved in transferring a file to the backup with Reverse Delta, followed by Step 4, which may be repeated indefinitely. Step 5 shows how older backups can be deleted, and Step 6 shows how a particular version of the file is restored from the delta files.

Click on the thumbnail image to open a PDF version of the image.