Samba gives me 24 MB/s read and 44 MB/s write, while ftp gives 97 and 112 MB/s under the same circumstances.

The documentation says that

Generally, you should find that Samba performs similarly to ftp at raw transfer speed.

In my case it clearly doesn't.

Where can I find tips on how to debug Samba performance?

Or alternatively tips for replacing Samba with something else? (I can't use ftp, unfortunately, as I need something that can be used with rsync/rsnapshot.)

More details:

• Both computers are running Ubuntu 10.10 (using Samba because I have a Mac as well)

• The Samba share is on a local home network, mounted as

  $ mount
  ...
  //server.local/share/ on /mnt/share type cifs (rw,mand)
  

• Samba performance was tested by copying (cp) a single file of ~4GB to and from the share, using time for timing and calculating transfer speed by hand.

• ftp performance are the numbers from the ftp client for get/put of the same file.
• iperf gives network speed ~900 Mbits/s
• bonnie++ gives disk speeds >200 MB/s on both sides for block reads as well as block writes
• Tried changing the parameters suggested in the performance tuning HOWTO (read/write raw, read size, socket options), most of them made little to no difference. (The one that made a difference caused write speed to drop 50%.)