Partial File Updating
Partial File Updating is a feature that makes updating of large files faster if only some parts of
the files have changed. This could be true especially for large databases such as Outlook .pst files.
Partial updating needs to have fast access to at least one of the sides of the synchronization. The
other side may be a low-bandwidth connection.
This feature can work in two different modes:
-
Mode 1:
- Source access must be fast
- Destination may be slow
- MD5 checksums are stored in database
- Destination files must not be modified by any other profile, person, or tool
-
Mode 2:
- ExtremeSync Remote Service computes MD5 checksums on remote computer
- The "slow" side can be both source or destination
- MD5 checksums are newly calculated each time
- Files on both sides can be modified by other profiles, persons, or tools
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 a slow connection, but it must be a normal file system (either LAN or VPN) or SSH/SFTP.
For other connections, you can use the new Synthetic Backup feature in version 5.
Instructions for Mode 1
In your profile, make the following checkmark: Use Partial File Updating, which is on the Specials tab sheet when editing the profile in Advanced Mode. The next time you run the profile, a .syncfdb 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.
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: With ExtremeSync Remote Service
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 has to be running Windows or MacOS.
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), or it can use SSH. 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.
For other connections, you can use the new Synthetic Backup feature in version 5.
Instructions for Mode 2
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-hand 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 Specials tab sheet in
Advanced Mode, make the following checkmarks: Use
Partial File Updating and Right side uses Remote
Service.
The Remote Service is also documented here.
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.