[lug] NSLU2 as backup device

[bgiles at coyotesong.com]

> Bear Giles wrote:
> [...]
>> I set up rdiff-backup and have run it against my desktop several times.
>> It took about 6 hours to sync an unmodified 10 GB dataset.  Maybe it's
>> SSH killing me, or maybe it's just too underpowered for this.
>
> So that's 485KBps or 3.9Mbps.  Be interesting if you could figure out
> the bottleneck.  But your guess of CPU vs. SSH sounds good to me (you
> could always try it over rsh).  And the NSLU2 probably wasn't designed
> with throughput in mind.

As the coffee hits... I remember that there should be fairly light network
traffic since very little of the data has actually changed.  IIRC the
protocol starts with comparing the size and MD5(?) hash of the files and
if they match it moves on to the next file.  (Even modified files may not
be copied in their entirety.)  Literally 99.9+% of all files would have
been unmodified.

The next most likely culprit is probably computing the hashes... unless
that's cached somewhere.