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Better Edge Backup v5.2
User Guide
Copyright © 2008, Better Edge Technology, Inc. All Rights Reserved.
Page 55 of 121 (September 16, 2008)
8 In-File Delta Technology
The chapter describes what in-file delta technology is and how in-file delta can be used to backup large database
files (e.g. a 10GB Outlook.pst file) without uploading the whole database file everyday.
8.1 Overview
In-file delta technology is an advanced data block matching algorithm which has the intelligence to pick up
changes (delta) of file content between two files. Using this algorithm, daily backing up of large files (e.g. a 10GB
Outlook.pst file) over low-speed internet connection is made possible because it requires only the changes of
information (should be marginal) since the last backup to be sent over a low-speed internet connection to
complete the backup of a large file (here we assume that the full backup of the file has been saved on the backup
server already).
This is what will happen in the backup of a 10GB Outlook.pst file when it is backed up by Better Edge Backup with
in-file delta technology.
i. The whole files (10GB), along with its checksum file, are backed up to the backup server. This can
be done directly through the internet or indirectly using the seed loading utility on a removable
hard disk.
ii. When backup runs again later (normally the next day), Better Edge Backup will download a
checksum listing of all data blocks of the full backup file (or last incremental backup file) from the
backup server and use it to pick up all changes that have been made to the current Outlook.pst
file.
iii. Changes detected are then saved in a delta file which is uploaded to the backup server. A new
checksum file is generated and is also uploaded. (This delta file is assumed to be small because
the content of PST files doesn’t change a lot during daily usage)
iv. Subsequent backups of this 10GB Outlook.pst file will go through step ii and step iii again. As
explained, only a small delta file and checksum file will be uploaded to the backup server.
v. With in-file delta technology, daily backing up of large file over low-speed internet connection is
now possible
Incremental in-file delta type
Incremental Delta will facilitate ease of backup. The delta is generated by comparing with the latest uploaded full
or delta file. The delta file generated is the smallest possible and uses the least bandwidth during backup. For
restoration, the full file and all delta files up to the required point-in-time is required to restore the file to a
specific point-in-time.
Example: If you are adding around 100MB changes to a 10G Outlook.pst everyday.
After the first full backup job, Better Edge Backup will continue to generate and upload delta files instead of
uploading the full file until either one of the following two rules are true:
a) Number of deltas generated since the last full backup is greater than the [Number of Delta] setting.
b) The delta ratio (the ratio of the delta file size against the full file size) is greater than the [Delta Ratio]
setting
Using incremental delta, the delta generated by comparing the current file with the latest uploaded full or delta
file is around 100MB.
Since the delta file size is around 100MB daily, the delta ratio (around 1%) will not trigger a full file upload.
Instead Better Edge Backup will continue to generate and upload delta files until day 102 (assuming the full file
was uploaded on day 1) when the number of deltas generated exceeds the [Number of Delta] setting and triggers
the upload of the full Outlook.pst file. You can disable the [Number of Delta] and [Delta Ratio] if you don’t want to
upload the full file.