From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Tue, 11 Dec 2007 15:14:17 -0800 (PST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.168.28]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id lBBNEAB3007751 for ; Tue, 11 Dec 2007 15:14:12 -0800 Received: from mail.lichtvoll.de (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 3644810FA446 for ; Tue, 11 Dec 2007 15:14:20 -0800 (PST) Received: from mail.lichtvoll.de (mondschein.lichtvoll.de [194.150.191.11]) by cuda.sgi.com with ESMTP id SechnEgai1hzDiZq for ; Tue, 11 Dec 2007 15:14:20 -0800 (PST) Received: from [192.168.1.21] (dslb-084-056-075-184.pools.arcor-ip.net [84.56.75.184]) by mail.lichtvoll.de (Postfix) with ESMTP id 3799A5ADDC for ; Tue, 11 Dec 2007 23:40:41 +0100 (CET) From: Martin Steigerwald Subject: write barrier over device mapper supported or not? Date: Tue, 11 Dec 2007 23:42:23 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200712112342.24094.Martin@lichtvoll.de> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: linux-xfs@oss.sgi.com Hello! Are write barriers over device mapper supported or not? On LVM2 xfs tells me: Dec 11 23:00:09 shambala kernel: Filesystem "dm-0": Disabling barriers, not supported by the underlying device Dec 11 23:00:09 shambala kernel: XFS mounting filesystem dm-0 Dec 11 23:00:09 shambala kernel: Ending clean XFS mount for filesystem: dm-0 But when I mount ext3 on LVM2 I get: Dec 11 23:05:34 shambala kernel: kjournald starting. Commit interval 5 seconds Dec 11 23:05:34 shambala kernel: EXT3 FS on dm-1, internal journal Dec 11 23:05:34 shambala kernel: EXT3-fs: mounted filesystem with ordered data mode. even when I explicetely specify "-o barrier=1" which should enable barriers on ext3. As far as I understood from the changelogs as I wrote my Linux-Magazin I thought there should be device mapper support in the kernel, but I can not reproduce that finding anymore at the moment. But back then I also looked at the ext3 / jbd sources and found that jbd issues a warning when barrier support is not available. However I do not find that one either. And when I use reisferfs it also seems that write barriers are not available over LVM2: Dec 11 23:34:58 shambala kernel: ReiserFS: dm-2: found reiserfs format "3.6" with standard journal Dec 11 23:34:58 shambala kernel: ReiserFS: dm-2: using ordered data mode Dec 11 23:34:58 shambala kernel: reiserfs: using flush barriers Dec 11 23:34:58 shambala kernel: ReiserFS: dm-2: journal params: device dm-2, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30 Dec 11 23:34:58 shambala kernel: ReiserFS: dm-2: checking transaction log (dm-2) Dec 11 23:35:01 shambala kernel: reiserfs: disabling flush barriers on dm-2 Dec 11 23:35:01 shambala kernel: ReiserFS: dm-2: Using r5 hash to sort names Dec 11 23:35:01 shambala kernel: ReiserFS: dm-2: warning: Created .reiserfs_priv on dm-2 - reserved for xattr storage. Hmmm... too bad... means I will likely not use LVM on my next laptop harddisk. I think I should file a kernel bug report about that. Anyone knows of any plans to support write barriers via device mapper? Well I guess I should ask on dm-devel or so if such a mailinglist exists. Ciao, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7