Keep one BIG file in sync

Martin Pool mbp at
Sat Feb 23 08:56:41 EST 2002

On 21 Feb 2002, Oliver Krause <krauseo at> wrote:
> Hi,
> after some searching i didn't came up with an answer so please excuse if this 
> is a total newbie question.
> My problem:
> I have server A which has a big (>500G) database like file. On server B i 
> want to have a copy of this file which i don't want to copy each time but 
> sync the deltas so that only the deltas are written once a day. Bandwidth 
> between A and B isn't the problem. The sync should be as fast as
> possible.

rsync should work well, though as Dave noted you need enough disk
space on the destination machine to hold a second temporary copy
during transfer.

Memory usage should be moderate.  If not, report a bug.

If you're feeling adventurous, you might like to investigate the rdiff
tool available from  This might give you a reduction
in the amount of disk IO compared to rsync, depending on the load.


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