From: Lukas Czerner Subject: Re: [dm-devel] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target] Date: Mon, 2 May 2011 16:39:31 +0200 (CEST) Message-ID: References: <20110413224025.GA18589@redhat.com> <20110413234854.GA19793@redhat.com> <20110426173213.GA19604@redhat.com> <20110428001912.GA14659@redhat.com> <20110428075355.GA2190@infradead.org> <20110428205935.GA24979@redhat.com> <20110429122454.GL32370@agk-dp.fab.redhat.com> <20110502081308.GC8642@agk-dp.fab.redhat.com> <20110502081925.GA11312@infradead.org> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-872738970-1304347175=:3778" Cc: Lukas Czerner , Christoph Hellwig , device-mapper development , Alasdair G Kergon , sandeen@redhat.com, Mike Snitzer , DarkNovaNick@gmail.com, linux-lvm@redhat.com, linux-ext4@vger.kernel.org To: "Martin K. Petersen" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:63887 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759440Ab1EBOkB (ORCPT ); Mon, 2 May 2011 10:40:01 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-872738970-1304347175=:3778 Content-Type: TEXT/PLAIN; charset=ISO-8859-2 Content-Transfer-Encoding: 8BIT On Mon, 2 May 2011, Martin K. Petersen wrote: > >>>>> "Lukas" == Lukas Czerner writes: > > Lukas> So I gave it a try. First of all the device composed of SSD and > Lukas> spinning disk does export discard_support information properly, > Lukas> however it also advertise discard_zeroes_data which is wrong and > Lukas> possibly dangerous and should be fixed! > > I can't reproduce this here. If I mix discard and non-discard devices > things work correctly. discard_zeroes_data also gets cleared if I mix > discard-capable drives where one zeroes and one doesn't. > > [root@trim ~]# hdparm -I /dev/sdb | grep -i trim [root@trim ~]# cat /sys/block/sdb/queue/discard_zeroes_data 0 [root@trim ~]# hdparm -I /dev/sdd | grep -i trim * Data Set Management TRIM supported * Deterministic read after TRIM [root@trim ~]# cat /sys/block/sdd/queue/discard_zeroes_data 1 [root@trim ~]# pvcreate /dev/sdd1 Physical volume "/dev/sdd1" successfully created [root@trim ~]# pvcreate /dev/sdb3 Physical volume "/dev/sdb3" successfully created [root@trim ~]# vgcreate vg_test /dev/sdd1 /dev/sdb3 Volume group "vg_test" successfully created [root@trim ~]# lvcreate -L 3500M vg_test Logical volume "lvol0" created [root@trim ~]# ls -lah /dev/mapper/vg_test-lvol0 lrwxrwxrwx. 1 root root 7 2.?kv? 10.30 /dev/mapper/vg_test-lvol0 -> ../dm-0 [root@trim ~]# cat /sys/block/dm-0/queue/discard_zeroes_data 1 [root@trim ~]# uname -r 2.6.39-rc5-blkdev+ [root@trim ~]# cat /proc/partitions 8 19 1951897 sdb3 8 49 1951866 sdd1 253 0 3584000 dm-0 So I assume it got fixes just recently ?. I'll give it a try with the up-to-date kernel. Thanks! -Lukas --8323328-872738970-1304347175=:3778--