From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [10.32.4.9] (vpn-4-9.str.redhat.com [10.32.4.9]) by pobox.stuttgart.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id l8KKQtoO017551 for ; Thu, 20 Sep 2007 22:26:55 +0200 Message-ID: <46F2D78F.5020705@redhat.com> Date: Thu, 20 Sep 2007 22:26:55 +0200 From: Milan Broz MIME-Version: 1.0 Subject: Re: [linux-lvm] exception when snapshot size is less than the volume size References: <258405.7001.qm@web33603.mail.mud.yahoo.com> In-Reply-To: <258405.7001.qm@web33603.mail.mud.yahoo.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Hi, this is an old snapshot bug, already fixed in all recent kernels - see http://bugzilla.kernel.org/show_bug.cgi?id=7040 Plese could you try to apply patch mentioned in this bugzilla ? also here http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.18.y.git;a=commitdiff;h=2b64e22fdbc35b4a0e7c1cbda590daaced401c35;hp=6e28fa8b0390dcbb883994f3c634c1f56fe4f93a (or simply use latest stable 2.6.18.8 kernel) Milan -- mbroz@redhat.com Sagar Borikar wrote: > In my NAS box, I observed strange thing yesterday. I had the snapshot > size (32MB) less than volume size was (10 GB) You can say I was trying > to do failure analysis of my box. The LVM HOwto for snapshot says > " > ** > > > If the snapshot logical volume becomes full it will be dropped (become > unusable) so it is vitally important to allocate enough space. The > amount of space necessary is dependent on the usage of the snapshot, so > there is no set recipe to follow for this. If the snapshot size equals > the origin size, it will never overflow. > > " > But my box was crashed in this scenario. > Was wondering why didn't it disable the snapshots. > The underlying processor is MIPS and linux kernel version is 2.6.18. > After delving little bit in the sources I found that break is occurring > while blowing away the snapshot facility -- so it`s not surprising that > snapshots do not work anymore. Just before the error, > kcopyd_client_destroy is called -- so that`s it for kcopyd jobs -- hence > snapshots. The snapshot faciltiy is gone at that point, with or without > the BUG_ON. The error actually occurs while freeing the exception tables > in the slab cache. > > Any pointers if this has been resolved? > I am working with lvm version 2.02.28. and device mapper version 1.02.22