From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754566AbZHTOiU (ORCPT ); Thu, 20 Aug 2009 10:38:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754528AbZHTOiT (ORCPT ); Thu, 20 Aug 2009 10:38:19 -0400 Received: from rtr.ca ([76.10.145.34]:41027 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754377AbZHTOiS (ORCPT ); Thu, 20 Aug 2009 10:38:18 -0400 Message-ID: <4A8D5FDB.7080505@rtr.ca> Date: Thu, 20 Aug 2009 10:38:19 -0400 From: Mark Lord Organization: Real-Time Remedies Inc. User-Agent: Thunderbird 2.0.0.22 (X11/20090608) MIME-Version: 1.0 To: Ric Wheeler Cc: Ingo Molnar , Christoph Hellwig , Peter Zijlstra , Paul Mackerras , Linus Torvalds , xfs@oss.sgi.com, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, jens.axboe@oracle.com, IDE/ATA development list , Neil Brown Subject: Re: [PATCH, RFC] xfs: batched discard support References: <20090816004705.GA7347@infradead.org> <20090819203916.GA25296@elte.hu> <4A8CA956.2060406@rtr.ca> <4A8D5442.1000302@redhat.com> In-Reply-To: <4A8D5442.1000302@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ric Wheeler wrote: > > Note that returning consistent data is critical for devices that are > used in a RAID group since you will need each RAID block that is used to > compute the parity to continue to return the same data until you > overwrite it with new data :-) > > If we have a device that does not support this (or is misconfigured not > to do this), we should not use those devices in an MD group & do discard > against it... .. Well, that's a bit drastic. But the RAID software should at least not issue TRIM commands in ignorance of such. Would it still be okay to do the TRIMs when the entire parity stripe (across all members) is being discarded? (As opposed to just partial data there being dropped)