From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Majed B." Subject: Re: Re-map disk sectors in userspace when rewriting after read errors Date: Fri, 18 Sep 2009 12:57:23 +0300 Message-ID: <70ed7c3e0909180257hf13ba48va808b942deaba177@mail.gmail.com> References: <87ws3z5iro.fsf@frosties.localdomain> <1253106813.17888.9.camel@localhost> <70ed7c3e0909180117v725982dr5c6a344586ba36eb@mail.gmail.com> <20090918082851.GD22909@cthulhu.home.robinhill.me.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20090918082851.GD22909@cthulhu.home.robinhill.me.uk> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Thank you for the insight, Robin. I already have used dd_rescue to find which sectors are bad, so I guess I could either wait for Matthias to finish his modifications to mdadm, or I can reconstruct the bad sectors manually (read same sector from other disks, xor all, write to damaged disk's clone). Weird thing though, is that when I re-read some of the bad sectors, I didn't get I/O errors ... it's confusing! Also, I'd rather avoid a fsck when I have bad sectors to not lose files. I'll run fsck once I've fixed the bad sectors and resynced the array. On Fri, Sep 18, 2009 at 11:28 AM, Robin Hill wr= ote: > All the 'check' action does is validate that the checksum matches the > data. =C2=A0By doing this, it will also be doing a full read check on= the > array (though I'm not certain what action is taken on read failures). > The 'repair' action will also rewrite any checksums which don't match > the data. > > All of this requires a non-degraded array, so I suspect the 'check' a= nd > 'repair' actions will get ignored altogether on a degraded array (and > certainly won't actually work). =C2=A0As the array is degraded, you _= can't_ > have any RAID inconsistencies. =C2=A0You may have some filesystem > inconsistencies (a fsck is definitely recommended) and/or data > inconsistencies (unless you have checksums or backups to compare agai= nst > then you're stuck on finding these though). > > Cheers, > =C2=A0 =C2=A0Robin > -- > =C2=A0 =C2=A0 ___ > =C2=A0 =C2=A0( ' } =C2=A0 =C2=A0 | =C2=A0 =C2=A0 =C2=A0 Robin Hill =C2= =A0 =C2=A0 =C2=A0 =C2=A0 | > =C2=A0 / / ) =C2=A0 =C2=A0 =C2=A0| Little Jim says .... =C2=A0 =C2=A0= =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0| > =C2=A0// !! =C2=A0 =C2=A0 =C2=A0 | =C2=A0 =C2=A0 =C2=A0"He fallen in = de water !!" =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 | > --=20 Majed B. -- 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