Copy only changes in a file

[Mark Minnie]

I want to synchronize two directories across a WAN. I know there are
dozens of programs to do this, but I can't find a program that will
only copy the changes in file.


For example...I have dozens and dozens of files ranging from 2MB to
500MB. These files change on a daily basis, but each file only
changes slightly. Because of the WAN bandwidth, I want to minimize
the data transfer. If the 500MB file changes, I don't see a need to
copy the entire 500MB if only a tiny portion of the file has changed.
I want to copy only the changed section of the file.

I think pcAnywhere uses a client-server between the apps on two
computers to do a binary check of what has changed between the files.
Only the changes are copied during a pcAnywhere "Speed Send". I
think that is what it is called in pcAnywhere.

Does anyone know of an application that copies only a portion of the
file besides pcAnywhere?

 

[SG]

Hi Mark,

Not sure on this, but read about it and it may do what you want.
http://www.microsoft.com/windowsxp/using/digitalphotography/prophoto/synctoy.mspx

All the best,
SG

 

[HeyBub]

I want to synchronize two directories across a WAN. I know there are
dozens of programs to do this, but I can't find a program that will
only copy the changes in file.


For example...I have dozens and dozens of files ranging from 2MB to
500MB. These files change on a daily basis, but each file only
changes slightly. Because of the WAN bandwidth, I want to minimize
the data transfer. If the 500MB file changes, I don't see a need to
copy the entire 500MB if only a tiny portion of the file has changed.
I want to copy only the changed section of the file.

I think pcAnywhere uses a client-server between the apps on two
computers to do a binary check of what has changed between the files.
Only the changes are copied during a pcAnywhere "Speed Send". I
think that is what it is called in pcAnywhere.

Does anyone know of an application that copies only a portion of the
file besides pcAnywhere?

There are several ways to attack the problem. The easiest is a "patch"
technique. In this technique:

1. The new file is compared to an old file and the differences recorded in a
3rd file.
2. The 3rd file is then used to "patch" some other file(s).

You would have to retain a copy of the old file on your current machine in
order to create the patch file. You then ship the patch file to another
computer. On that other computer, a "patch" program runs to apply the
patches.

Use Google to find "difference" and "patch" programs