Date: Wed, 18 Jul 2012 16:34:37 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: "CH" <freebsd-fs@ch.pkts.ca>, "Kai Gallasch" <gallasch@free.de> Cc: freebsd-fs@freebsd.org Subject: Re: Can you list internal checksums of a ZFS filesystem? Message-ID: <8A24A3EFF4314670BAED740A02373F27@multiplay.co.uk> References: <20120717152629.42e0641e@fedora14-x86-64.shechinah.mi.microbiology.ubc.ca><6D778EEA-5B8F-4F59-B198-E5B098F3AE2C@free.de> <20120718075754.4908266b@kirk.lan>
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----- Original Message -----
From: "CH" <freebsd-fs@ch.pkts.ca>
> Actually, I did do rsync for the initial transfers, and it had to be
> restarted a couple of times for reasons that were not its fault (source
> computer rebooted, ssh connection lost, etc). However, after it
> finished copying everything (ie: exiting normally), I ran it again, and
> it found more stuff to copy. This shouldn't have happened since
> nothing was added to the source computer, and so now I distrust its
> results and want to check it independently. In particular, I don't
> trust its directory-walking algorithm, so some files may have been
> missed and may continue to be missed in future runs of rsync, with or
> without -c.
>
> The method I was going to use was 'find . -type f -print0 | xargs -0
> md5sum > my.big.md5sum.file' on both source and destination, but if I
> can harvest the ZFS checksums (file or block) it would cut the cpu
> workload in half, and save a tree's worth of energy.
rsync is reliable when run on run cleanly. If like you had interruptions
and you where running using say -av then it can miss changes if files
changed but size or timestamps didn't.
I've never had an run complete cleanly with a re-run detecting new
files where files weren't in fact added.
As mentioned --checksum (-c) forces checksums to be compared on both
ends which will allow you to verify all is good.
Regards
Steve
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