Speeding up rsync over smb

Solution 1:

I think you're having a misunderstanding of the rsync algorithm and how the tool should be applied.

Rsync's performance advantage comes from doing delta transfers-- that is, moving only the changed bits in a file. In order to determine the changed bits, the file has to be read by the source and destination hosts and block checksums compared to determine which bits changed. This is the "magic" part of rsync-- the rsync algorithm itself.

When you're mounting the destination volume with SMB and using rsync to copy files from what Linux "sees" as a local source and a local destination (both mounted on that machine), most modern rsync versions switch to 'whole file' copy mode, and switch off the delta copy algorithm. This is a "win" because, with the delta-copy algorithm on, rsync would read the entire destination file (over the wire from the NAS) in order to determine what bits of the file have changed.

The "right way" to use rsync is to run the rsync server on one machine and the rsync client on the other. Each machine will read files from its own local storage (which should be very fast), agree on what bits of the files have changed, and only transfer those bits. They way you're using rsync amounts of a trumped-up 'cp'. You could accomplish the same thing with 'cp' and it would probably be faster.

If your NAS device supports running an rsync server (or client) then you're in business. If you're just going to mount it on the source machine via SMB then you might as well just use 'cp' to copy the files.

Solution 2:

It sounds like timestamps are your problem, as this page relates:

http://www.goodjobsucking.com/?p=16

The proposed solution is to add

--modify-window=1

to the rsync parameters.