Date: Tue, 26 Aug 2014 09:44:46 -0400 From: Paul Kraus <paul@kraus-haus.org> To: Scott Bennett <bennett@sdf.org> Cc: freebsd-questions@freebsd.org, freebsd@qeng-ho.org, Trond.Endrestol@fagskolen.gjovik.no Subject: Re: gvinum raid5 vs. ZFS raidz Message-ID: <9588077E-1198-45AF-8C4A-606C46C6E4F8@kraus-haus.org> In-Reply-To: <201408260641.s7Q6feBc004970@sdf.org> References: <201408020621.s726LsiA024208@sdf.org> <alpine.BSF.2.11.1408020356250.1128@wonkity.com> <53DCDBE8.8060704@qeng-ho.org> <201408060556.s765uKJA026937@sdf.org> <53E1FF5F.1050500@qeng-ho.org> <201408070831.s778VhJc015365@sdf.org> <alpine.BSF.2.11.1408071034510.64214@mail.fig.ol.no> <201408070936.s779akMv017524@sdf.org> <alpine.BSF.2.11.1408071226020.64214@mail.fig.ol.no> <201408071106.s77B6JCI005742@sdf.org> <5B99AAB4-C8CB-45A9-A6F0-1F8B08221917@kraus-haus.org> <201408220940.s7M9e6pZ008296@sdf.org> <7971D6CA-AEE3-447D-8D09-8AC0B9CC6DBE@kraus-haus.org> <201408260641.s7Q6feBc004970@sdf.org>
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On Aug 26, 2014, at 2:41, Scott Bennett <bennett@sdf.org> wrote: > Paul Kraus <paul@kraus-haus.org> wrote: >> On Aug 22, 2014, at 5:40, Scott Bennett <bennett@sdf.org> wrote: >>> What I'm seeing here is ~2 KB of errors out >>> of ~1.1TB, which is an error rate (in bytes, not bits) of ~1.82e+09, = and the >>> majority of the erroneous bytes I looked at had multibit errors. I = consider >>> that to be a huge change in the actual device error rates, specs be = damned. >>=20 >> That seems like a very high error rate. Is the drive reporting those = errors or are they getting past the drive?s error correction and showing = up as checksum errors in ZFS ? A drive that is throwing that many errors = is clearly defective or dying. >=20 > I'm not using ZFS yet. Once I get a couple more 2 TB drives, I'll = give > it a shot. > The numbers are from running direct comparisons between the source = file > and the copy of it using cmp(1). In one case, I ran the cmp twice and = got > identical results, which I interpret as an indication that the errors = are > occurring during the writes to the target disk during the copying. Wow. That implies you are hitting a drive with a very high uncorrectable = error rate since the drive did not report any errors and the data is = corrupt. I have yet to run into one of those. -- Paul Kraus paul@kraus-haus.org
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