From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maurilio Longo Subject: Re: Bad blocks are killing us! Date: Tue, 16 Nov 2004 17:28:47 +0100 Message-ID: <419A2ABF.623A126A@libero.it> References: <200411150522.iAF5MNN18341@www.watkins-home.com> <16793.11589.337840.541169@cse.unsw.edu.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Guy Watkins , linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil Brown ha scritto: > On Monday November 15, guy@watkins-home.com wrote: > > Neil, > > This is a private email. You can post it if you want. > snip > > > > Anyway, in the past there have been threads about correcting bad > > blocks automatically within md. I think a RAID1 patch was created that will > > attempt to correct a bad block automatically. Is it likely that you will > > pursue this for RAID5 and maybe RAID6? I hope so. > > My current plans for md are: [...] > > 2/ Look at recovering from failed reads that can be fixed by a > write. I am considering leveraging the "bitmap resync" stuff for > this. With the bitmap stuff in place, you can let the kernel kick > out a drive that has a read error, let user-space have a quick > look at the drive and see if it might be a recoverable error, and > then give the drive back to the kernel. It will then do a partial > resync based on the bitmap information, thus writing the bad > blocks, and all should be fine. This would mean re-writing > several megabytes instead of a few sectors, but I don't think that > is a big cost. There are a few issues that make it a bit less > trivial than that, but it will probably be my starting point. > The new "faulty" personality will allow this to be tested easily. > I think 2/ should go unattended for at least a few retries, then, if they all fail, kick-out disk and/or call user-space program to see what's going on, I say this because an occasional read error should not kick-out a disk or require user intervention to fix it (as it is now). And it seems to me that new disks have a lot of badsectors regardless their brand. just my .02 euro cents :) regards. -- __________ | | | |__| md2520@mclink.it |_|_|_|____| Team OS/2 Italia