I am attempting to perform a backup using rsync of some files on a Digital Ocean VPS running Ubuntu 14.04.4 LTS.
rsync is extremely slow, ranging from 20-50 kB/s, only 1% of what it should be. It is equally slow when using scp or when using rsync in daemon mode, so this does not seem to be a problem particular to rsync or ssh.
I also have access to another VPS (Linode), I get the expected transfer speeds of 2-3MB/s when transferring files using rsync from that VPS.
Also, when I transfer files using rsync directly from the Digital Ocean VPS to the Linode VPS I get normal inter-server transfer rates of 15MB/s. These factors combined indicate that ssh and rsync are working fine on all the machines.
For now I've circumvented the problem by tunneling the ssh connection via the Linode VPS, but I'm curious about what might be causing the very low transfer rates.