[rdiff-backup-users] Quick question - Can rdiff (or anything else) do this?

[Edward Harvey]

I have some large files, such as hard drive images for virtual machines,  which will change a few blocks at a time but most of the file remains unchanged, and I would like to backup efficiently.  Needless to say it is bad to send the whole file across every time.  I would like a diff-like program which will analyze the file in chunks, and only send across the chunks which changed from last time.  This would gain little or no performance boost if copying from disk-to-disk, but when there is a WAN in between the source and destination, it could greatly improve the transfer time.

Can rdiff (or anything that anyone knows of) do this?

Thank you.