Date: Fri, 06 Jan 2012 16:49:22 -0500 From: Boris Kochergin <spawk@acm.poly.edu> To: Gareth de Vaux <bsd@lordcow.org> Cc: stable@freebsd.org Subject: Re: gmirror not synced Message-ID: <4F076C62.6060604@acm.poly.edu> In-Reply-To: <20120104194313.GA2558@lordcow.org> References: <20120104194313.GA2558@lordcow.org>
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On 01/04/12 14:43, Gareth de Vaux wrote: > Hi all, I've noticed that the md5 hashes of a couple of files on > a gmirror change when I recalculate the hashes. The output usually > cycles between 2 hashes per file. > > I'm guessing this is because each calculation reads the file > randomly from 1 of 2 component drives, and the files in question > had a few bit flips during their original sync. I also assume > this's something you have to live with for gmirror? Is removing > and completely rebuilding the secondary drive the only thing you > can do (which might fix these bit flips but incur others elsewhere)? > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" Hi. Bit-flipping is unlikely, but, you can test this hypothesis by having it only ever read from one disk. Use "gmirror configure -b" to change the balancing algorithm of the array to priority and "gmirror configure -p" to change the priority one of of the members. Then, repeat the test for the other member. What I would say is more likely is that you've got bad memory or CPU cache in the machine. I've had this happen to me and that turned out to be the case. And, as the other reply said, it's a good idea to make sure you've got a good backup at this point. -Boris
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