[rdiff-backup-users] Poor Restoration Performance

[Dean Cording]

I've recently had need to restore my complete system from an rdiff-backup 
backup and I was struck by the poor performance it exhibited - Restoring 6GB 
of data took over 12 hours.  I'm located in Australia and my backups are 
hosted on Amazon Web Services on the east coast of the US (can't get much more 
offsite than that!).  

Investigations showed that neither the CPUs on either end nor the network link 
were the limiting factor.  In fact, I was able to run three simultaneous 
restore sessions with no degraded performance before the network link became 
saturated.

This suggests that network latency (typically 250ms in my case) is the 
determinate factor for the restore performance.  Whilst I don't know much 
about the details of the protocol, it might be possible to speed up rdiff-
backup by using larger blocks or windowing.

Dean