From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hardcastle Subject: Re: Fw: Why does one get mismatches? Date: Sun, 24 Jan 2010 09:40:42 -0800 (PST) Message-ID: <65698.36235.qm@web51306.mail.re2.yahoo.com> References: <877hra57pf.fsf@frosties.localdomain> Reply-To: Jon@eHardcastle.com Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <877hra57pf.fsf@frosties.localdomain> Sender: linux-raid-owner@vger.kernel.org To: Jon@eHardcastle.com, Goswin von Brederlow Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --- On Fri, 22/1/10, Goswin von Brederlow wrote: > From: Goswin von Brederlow > Subject: Re: Fw: Why does one get mismatches? > To: Jon@eHardcastle.com > Cc: linux-raid@vger.kernel.org > Date: Friday, 22 January, 2010, 18:13 > Jon Hardcastle > writes: >=20 > > --- On Tue, 19/1/10, Jon Hardcastle > wrote: > > > >> From: Jon Hardcastle > >> Subject: Why does one get mismatches? > >> To: linux-raid@vger.kernel.org > >> Date: Tuesday, 19 January, 2010, 10:04 > >> Hi, > >>=20 > >> I kicked off a check/repair cycle on my machine > after i > >> moved the phyiscal ordering of my drives around > and I am now > >> on my second check/repair cycle and it has kept > finding > >> mismatches. > >>=20 > >> Is it correct that the mismatch value after a > repair was > >> needed should equal the value present after a > check? What if > >> it doesn't? What does it mean if another check > STILL reveals > >> mismatches? > >>=20 > >> I had something similar after i reshaped from raid > 5 to 6 i > >> had to run check/repair/check/repair several times > before i > >> got my 0. > >>=20 > >>=20 > > > > Guys, > > > > Anyone got any suggestions here? I am now on my ~5 > check/repair and after a reboot the first check is still > returning 8. > > > > All i have done is move the drives around. It is the > same controllers/cables/etc=20 > > > > I really dont like the seeming random nature of what > can/does/has caused the mismatches? >=20 > There is some unknown corruption going on with raid1 that > causes > mismatches but it is believed that it will never occur on > any used > block. Swapping is a likely cause. >=20 > Any swap device on the raid? Try turning that off. > If that doesn't help try umounting filesystems or > remounting RO. >=20 > MfG > =A0 =A0 =A0 =A0 Goswin Hello, my usual savior Goswin! The deal is it is a 7 drive raid 6 array. it has LVM on it and is not u= sed for swapping. I have umounted all LV's and still got mismatches, i = run smartctl --test=3Dlong on all drives - nothing. I have now dismantl= ed the array and am 3/4 the way through 'badblocks -svn' on each of the= component drive. I have a hunch that it may be a dodgy SATA cable but = have no evidence. No errors in log, nothing on dmesg. Is there any way to get more information? I am starting to think this i= s more happened since i changed from raid 5 to 6..... which i did < 1 m= onth ago. The only lead i have is that whilst doing the bad blocks 1 drive ran at= ~10~15MB/s whereas the rest are going at ~30 i have another identical = model drive coming up so i will see if that one is slow too. But the la= ck of logging info is not helpful and worrying! and the prospect of sil= ent corruption a big worry! =20 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html