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Partial File Updating

See also the most current information on our web site.

Partial file updating can speed up backing up very large files of which only a portion changes each day. For example, Outlook .pst-files and SQL database files may be a good candidate for this setting. The feature is selected on the Edit Profiles - Advanced tab sheet.

This feature can work in different modes:

Mode 1: Slow Destination

In this mode, the speed-up is available when you copy files from a location to which you have fast access (preferably your own hard disk). The destination can be reached via slow connection, but it must be a normal file system (either LAN or VPN). Even when backing up from one fast hard disk to another, there can be a speed-up due to partial file updating!

The speed-up is achieved by storing MD5 checksums for copied files in a local database. Speed-up is not available for FTP, but it can be done using SSH/SFTP (Mode 1 only).

Instructions

In your profile, make the following checkmark: Use Partial File Updating, which is on the Advanced tab sheet in Advanced Mode. The next time you run the profile, a .syndb database is created on your hard drive where information needed for the speed-up is stored. The second time you run the profile, you should notice the speed-up.

Only files with a size of at least 400,000 bytes are affected by the speed-up. The file is handled in slices of 200,000 bytes each. An MD5 checksum is used to determine whether a slice has been changed and needs updating. Therefore, there is a minute, totally unrealistic chance that a change might not be detected.

Mode 2: Slow Source and/or destination

This mode can speed up updating large files in both directions. The remote computer can be both source and/or destination. This is achieved by running a small service application on the remote computer, which will create the necessary checksums when requested by the main application running on a different machine. To install the ExtremeSync Remote Service on the remote computer, you need to have administrative access to that system, which currently has to be running Windows. Check our web site for a Mac version of the ExtremeSync Remote Service.

The other (local) computer, where the main Super Flexible File Synchronizer is running, needs to have normal file system access to the remote computer (LAN or VPN). It needs to have write access to the remote computer so that it can save the checksum request file there. The MD5 checksums are created when needed, so that no database is being used.

Support for an FTP connection will be added in a later release.

Instructions

On the remote system, run the Setup program and install the ExtremeSync Remote Service along with its control panel. Start the control panel from the Super Flexible group in the Start menu.

On the tab sheet Configure Checksummer, enter the base folders that will be used for synchronization. Click Apply.

On the tab sheet Service Configuration, click on Install Service and Start. The service will be using the Windows System account by default. If this account doesn't have sufficient access privileges, you may have to change the account in Windows Control Panel -> Administrative Tools -> Services.

On the local system, you are running the main program, Super Flexible File Synchronizer. In your profile, the right side must be the remote system. Specify one of the folders which you have specified for the remote service to monitor. The left side should be your local folders, or a network drive with relatively fast access. On the Advanced tab sheet in Advanced Mode, make the following checkmarks: Use Partial File Updating and Right side uses Remote Service.

That's it! Subsequent file updates should be much faster, if the file already exists on both sides, and if only a portion of the file has changed.