In The Delta File Enhances Offsite Secure Backup Technology

We are all aware of the benefits accruing to a remote location. However, the biggest problem with backing up data over the Internet is explained as follows: -

Large files x low bandwidth = Massive backup time.

In delta-file greatly reduces this problem. 300GB up files can use the File Delta technology. This means basically, after initial file backup, only changes to this file will be sent to an external location. This makes secure offsite backup more usable for large databases, such as Microsoft Exchange.

Here you can learn what the file delta technology is and how delta file can be used for database backup files larger (eg a 10GB Outlook.pst file) without loading the database file of entire data data every day.


In the file delta technology is an advanced block of data matching algorithm which has the intelligence to pick up changes (delta) of file content between two files when a file is not accessible and use the delta information between two files to rebuild another file. The whole files (10GB), and the amount of file analysis (128 bits) are copied to the backup server. When the backup runs again later (normally the next day), PerfectBACKUP OBM will download a list of all full backup file data blocks from the backup server and use it to pick up all the changes that have been made the Outlook.pst file stream from the first full backup.

Detected changes are saved in a delta file that is sent to the backup server. (This delta file is assumed to be small because the content of all PST files does not change much, even after being updated)

Subsequent backups of this 10GB Outlook.pst file will go through step ii and iii stage again. As explained, only a small delta file will be sent to the backup server.

With technology delta in the file, the daily backup of a large file over low-speed internet connection is now possible

Example 1: If you are adding 200MB to Outlook.pst everyday, the first delta backup will upload a 200MB delta file and the next delta backup will upload a 400MB delta file. This will continue until day 50 when the delta file must be saved reaches 10GB. This delta file size (10GB) is now 50% of the Outlook.pst which is now 20GB (remember that you have added 100MB to this file everyday). If the [Delta Ratio] is set to 50% (default), the whole Outlook.pst file will be downloaded again.

Example 2: If you are adding 50MB to Outlook.pst everyday, the first delta backup will upload a 50MB delta file and the next delta backup will upload a 100MB delta file. All delta files are generated with respect to changes made since the last full backup file (ie differential backup). This means that only last full backup file and the last delta file are required to restore the latest snapshot of a backup file. This means that other intermediate delta files are only required if you want to restore other snapshots of a backup file.

Delta file differential backup rather than incremental backup. It is designed this way so that a corrupted delta file would only make one particular version of a backup file non-recoverable and all other backups created by other delta files of the same file would still be intact.

The full backup file, its control file and the last delta file uploaded (if more than one delta file was sent to the backup server) are always stored in the data area. All other intermediate delta files are stored in the retention zone.