From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3FCC906C.5040907@backtobasicsmgmt.com> From: "Kevin P. Fleming" MIME-Version: 1.0 References: <3FCB4AFB.3090700@backtobasicsmgmt.com> <20031201141144.GD12211@suse.de> <3FCB4CFA.4020302@backtobasicsmgmt.com> <20031201155143.GF12211@suse.de> <3FCC0EE0.9010207@backtobasicsmgmt.com> <20031202082713.GN12211@suse.de> <20031202211002.C2009778@wobbly.melbourne.sgi.com> In-Reply-To: <20031202211002.C2009778@wobbly.melbourne.sgi.com> Content-Transfer-Encoding: 7bit Subject: [linux-lvm] Re: Reproducable OOPS with MD RAID-5 on 2.6.0-test11 Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Tue Dec 2 07:16:02 2003 List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Nathan Scott Cc: Jens Axboe , LKML , Linux-raid maillist , linux-lvm@sistina.com Nathan Scott wrote: > One thing that might be of interest - XFS does tend to pass > variable size requests down to the block layer, and this has > tripped up md and other drivers in 2.4 in the distant past. > > Log IO is typically 512 byte aligned (as opposed to block or > page size aligned), as are IOs into several of XFS' metadata > structures. Hey, thanks for the pointer! I think we're getting somewhere now. Here's a recap of the tested combinations: XFS on raw disk: OK XFS on LVM2 on single disk: OK XFS on LVM2 on RAID-5: fails ext2 on LVM2 on RAID-5: OK I just tested XFS on LVM2 on RAID-5 using "-l sunit=8" while creating the filesystem to force log writes be block-sized and block-aligned; this seems to work :-) I have not been able to force a failure using my test script, although ATM the system is still running a RAID-5 resync of the array, but that should only make the problem more likely, not less. So, this does appear to be an md/dm stacking problem, that is exposed by XFS sending non-block-sized and/or non-block-aligned IOs.