From mboxrd@z Thu Jan 1 00:00:00 1970 From: chris Subject: Re: Weird Issue with raid 5+0 Date: Sun, 21 Feb 2010 02:26:42 -0500 Message-ID: <31e44a111002202326x407c814dsaa60e51a8a0ff049@mail.gmail.com> References: <31e44a111002202033m4a9dfba9yf8aef62b8b39933a@mail.gmail.com> <20100221164805.5bdc2d60@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20100221164805.5bdc2d60@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids That is exactly what I didn't want to hear :( I am running 2.6.26-2-xen-amd64. Are you sure its a kernel problem and nothing to do with my chunk/block sizes? If this is a bug what versions are affected, I'll build a new domU kernel and see if I can get it working there. - chris On Sun, Feb 21, 2010 at 12:48 AM, Neil Brown wrote: > On Sat, 20 Feb 2010 23:33:23 -0500 > chris wrote: > >> Hello, >> >> I am trying to setup a raid 5+0 on 6 1TB sata disks. I created the >> arrays like so: >> >> mdadm --create /dev/md2 --level=3D5 --raid-devices=3D2 /dev/sda /dev= /sdb /dev/sdc >> mdadm --create /dev/md3 --level=3D5 --raid-devices=3D2 /dev/sdd /dev= /sde /dev/sdf >> mdadm --create /dev/md4 --level=3D0 --raid-devices=3D2 /dev/md2 /dev= /md3 >> >> The arrays create and sync fine, then I put lvm on top and create a >> volume group and everything seems fine. I created 2 logical volumes >> and formatted them with filesystems and initially didn't realize >> anything was wrong. After running 2 virtual machines on them for a >> while =A0I noticed the vm's were reporting bad blocks on the volume.= I >> looked in the dom0 dmesg and found tons of messages such as: >> >> [444905.674655] raid0_make_request bug: can't convert block across >> chunks or bigger than 64k 69314431 4 > > This looks like a bug in 'dm' or more likely xen. > Assuming you are using a recent kernel (you didn't say), raid0 is > receiving a request that does not fit entirely in on chunk, and > which has more than on page in the bi_iovec. > i.e. bi_vcnt !=3D 1 or bi_idx !=3D 0. > > As raid0 has a merge_bvec_fn, dm should not be sending bios with more= than 1 > page without first cheking that the merge_bvec_fn accepts the extra p= age. > But the raid0 merge_bvec_fn will reject any bio which does not fit in > a chunk. > > dm-linear appears to honour the merge_bvec_fn of the underlying devic= e > in the implementation of its own merge_bvec_fn. =A0So presumably the = xen client > is not making the appropriate merge_bvec_fn call. > I am not very familiar with xen: =A0how exactly are you making the lo= gical > volume available to xen? > Also, what kernel are you running? > > NeilBrown > > >> >> Chunksize for both raid5's and the raid0 is 64k so it would appear t= he >> issue is not that the chunk size is greater than 64k. I also find it >> hard to believe it could be any kind of lvm issue simply because the >> message in dmesg clearly shows its related to the raid0. >> >> Any ideas on what I'm missing here would be greatly appreciated. I >> would imagine it is some kind of alignment between block and chunk >> sizes but I can't seem to figure it out :) >> >> More detailed information including raid information and errors is a= t >> http://pastebin.com/f6a52db74 >> >> - chris >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid= " in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > > -- 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