Re: [tlug] USB3 hard disks

[Josh Glover <jmglov@example.com>]

On 1 June 2014 09:15, Darren Cook <darren@example.com> wrote:

> So, we're talking slow, then. (If the whole 1TB disk can be mirrored in
> 5 minutes, it is quite practical to run it regularly.)

Once you've done the initial, time-consuming copy, subsequent rsyncs
will go much more quickly. The limiting factors there will be the read
speed of your source drive and the speed of your CPU in calculating
all of the hashes of file contents (I guess that rsync also makes use
of inode timestamps, when available, but you'd have to check the
manual to be sure about that). I doubt that your CPU will have any
trouble keeping up with the read speed of your drive, so that's likely
to be your bottleneck.

Depending on how much the contents of your source drive have changed,
while 5 minutes is probably quite optimistic, 30 or less might be
possible.

I'm sure others who are more familiar with rsync's mode(s) of
operation and USB drives can give you more specific info, but the main
point here is that the first full copy will be slow, but from then on,
keeping the drives in sync should go much faster, making running
regular syncs quite practical (of course, depending on *your*
definition of practical).


Cheers,
Josh