From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: [LSF/MM TOPIC] linux servers as a storage server - what'smissing? Date: Thu, 26 Jan 2012 17:29:02 -0500 Message-ID: <4F21D3AE.80806@redhat.com> References: <1326113987.2580.8.camel@localhost.localdomain> <4F18429C.3020803@redhat.com> <4F1844F0.1030406@redhat.com> <4F18566A.2060107@redhat.com> <4F188DA9.3050804@redhat.com> <20120126222428.GX15102@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Loke, Chetan" , Tom Coughlan , Hannes Reinecke , tasleson@redhat.com, Shyam_Iyer@Dell.com, vgoyal@redhat.com, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org To: Dave Chinner Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47344 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752275Ab2AZW3M (ORCPT ); Thu, 26 Jan 2012 17:29:12 -0500 In-Reply-To: <20120126222428.GX15102@dastard> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 01/26/2012 05:24 PM, Dave Chinner wrote: > On Tue, Jan 24, 2012 at 12:05:23PM -0500, Loke, Chetan wrote: >>>> But writes that have to fetch the non-cached data, will >> unnecessarily >>>> issue I/O to the fabric. These orphaned I/O's cause more pain in the >>>> cleanup. >>>> And if caching is enabled on the front-side then it's all the more >>>> painful. >>>> >>>> We can go one extra step and make FS fail read I/O for non-cached >> data >>>> too to avoid more orphan IOs. >>> I don't really see this as a useful state. Read-only without a real >>> backing file >>> system or LUN is hit or miss, that file system should go offline :) >>> >> Last year when I checked, I forget but I think xfs(or ext4) was going >> read-only. >> If this is still the case then you are basically asking FS's to modify >> that behavior. > ext4 goes read only on erro by default. I think that behaviour can > be changed by a mount option. > > XFS shuts the filesystem down (takes it offline) preventing all > dirty data and metadata from being issued to disk, aborts any > journal IO that might be going on, etc. It the returns fatal errors > (EIO or EUCLEAN "structure needs cleaning" errors) to all callers > that attempt to write or modify the filesystem, and EIO to all > attempts to read from it. > > IOWs, the XFS filesystem is *gone* once it shuts down and requires > administrator intervention to get it back to a working state.... > > Cheers, > > Dave. If it isn't obvious, I like the XFS approach :) Ric