From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: Call for RAID-6 users Date: Wed, 28 Jul 2004 09:36:37 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <41076595.7080403@dgreaves.com> References: <20040727021209.GA19205@jim.sh> <20040727172028.GA27240@jim.sh> <20040727181938.GA28181@jim.sh> <20040727184836.GA28494@jim.sh> <20040728030927.GA1625@jim.sh> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20040728030927.GA1625@jim.sh> To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Jim Paris wrote: >>And here's a trace showing problems even without a filesystem. >>Writing data near the end is fatal. This does not happen if I write >>to the first 1G of the array. >> >> > >Sorry, that test was bogus, and I needed to learn how to use mdadm. >I haven't actually managed to cause corruption on a raw device with no >filesystem. However, copying a single 200MB file onto Reiserfs will >cause corruption. It takes a lot more work (e.g. actually copying an >installed system onto it), but XFS shows eventual corruption as well, >so it's not specific to the filesystem type. > >I see no problems if I start the array with a complete set of disks; >the corruption only happens if it starts degraded (tested with both 1 >and 2 disks missing, and with the missing disks being at both the >beginning and the end). This happens on Linux 2.6.3 and 2.6.7, with >mdadm 1.5.0 and 1.4.0, with and without CONFIG_LBD. RAID-5 works >correctly in all tested configurations. I have tried varying the >number of disks in the array. > > > FWIW a month or so ago I used mdadm + 2.6.4 and constructed a 5x250Gb RAID 5 array with one drive missing. When I added the missing drive and reconstruction had finished I had fs corruption. I used the reiser tools to fix it but lost an awful lot of data. I reported it in detail here [http://marc.theaimsgroup.com/?l=linux-raid&m=108687793611905&w=2] and got zero response Since then it's been fine. I don't have much faith in it though ;) David PS around that time there was a patch [http://marc.theaimsgroup.com/?l=linux-raid&m=108635099921570&w=2] for a bug in the RAID5 resync code. it was only for the raid5.c It doesn't look raid5 algorithm specific ... :)