rsync over ssh - 50kbps

Question

This sync is taking all day, literally. Syncing from a mac (with rsync 3.0.5, from http://www.bombich.com/mactips/rsync.html) to Ubuntu with everything current. Internet is fast, computers are fast and not under load.

But bandwidth is orders of magnitude under capacity.

Am I doing something wrong?

Answer 1

What version of Mac OS X?

It's possible that you're running afoul of Mac OS X's TCP Delayed Ack algorithm. In most situations it increases performance, but in some cases it can hinder it. I can't know for sure that this is the problem from what you've told us so far, but it's quick to test. Try this:

1. Check what it's currently set to:

   sudo sysctl net.inet.tcp.delayed_ack

2. Turn if off:

   sudo sysctl -w net.inet.tcp.delayed_ack=0

3. Start a new sync.

If that alleviates the problem, you can set this permanently by created a file /etc/sysctl.conf and adding the line net.inet.tcp.delayed_ack=0 to it.

Answer 2

Please clarify what you mean by "internet is fast". Remember that you are UPLOADING from one of these machines, and upload is always slower (at least in aDSL, wich most homes and many business have).

Also, is there any other traffic using the same network? Especially if the mac is on a network with servers or other machines that have network stuff going on.