From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrei Banu Subject: Re: Weird jbd2 I/O load Date: Mon, 21 Oct 2013 17:24:45 +0300 Message-ID: <5265392D.1020500@redhost.ro> References: <525DB679.4070008@redhost.ro> <20131021135338.GA3392@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: linux-ext4@vger.kernel.org Return-path: Received: from gts6.roserve.net ([128.140.230.209]:59900 "EHLO gts6.roserve.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753200Ab3JUOZC (ORCPT ); Mon, 21 Oct 2013 10:25:02 -0400 Received: from 5-13-211-235.residential.rdsnet.ro ([5.13.211.235]:65389 helo=[127.0.0.1]) by gts6.roserve.net with esmtpsa (TLSv1:DHE-RSA-CAMELLIA256-SHA:256) (Exim 4.80.1) (envelope-from ) id 1VYGPg-00075l-21 for linux-ext4@vger.kernel.org; Mon, 21 Oct 2013 17:24:56 +0300 In-Reply-To: <20131021135338.GA3392@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Zheng, Thank you for your reply. We can make this test and if it doesn't help we'll re-enable the barrier but first I need to ask a few questions: 1. /dev/md2 is mounted on /. So your command should look like this? $ mount -t ext4 -o remount,barrier=0 /dev/md2 / In /etc/fstab I have other parameters as well: noatime,usrjquota=quota.user,jqfmt=vfsv0 Do I also add these like this: $ mount -t ext4 -o remount,barrier=0,noatime,usrjquota=quota.user,jqfmt=vfsv0 /dev/md2 / 2. Can the command above be run on an active (very active) cPanel server? 3. How do I re-enable the barrier? 4. What is the probability of data loss in case of cold reboot? Thanks! On 10/21/2013 4:53 PM, Zheng Liu wrote: > Hi Andrei, > > Could you please disable barrier for ext4 and try your 'dd' test again? > $ sudo mount -t ext4 -o remount,barrier=0 ${DEV} ${MNT} > > *WARNING: you could lost your data with barrier=0 when you get a power > failure or cold reset.* > > We have met a similar problem that is because some SSDs couldn't handle > barrier command properly. > > Regards, > - Zheng