Edward Savage <epssyis@gmail.com> writes:
tar --ignore-failed-read -C $SRC -cpf - . | tar --ignore-failed-read -C $DEST -xpvf - Home NAS devices are very CPU limited so compressing files is the last thing you want to do.
I don't see where he's compressing anything. OP: if you use tar you'll want to be root on both sides or you'll lose ownership &c stuff. Also you MAY want --numeric-owner.
An rsync still has to build file lists and calculate a hash for each but this process will be much faster. I suggest an initial rsync to move the bulk of the data and then a final pass when you're ready to stop using the NAS.
I would say just use rsync for both runs because it's less hassle, and if you interrupt it halfway you can pick up where you left off (tar obviously won't).