From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q7F6VNJB087678 for ; Wed, 15 Aug 2012 01:31:23 -0500 Received: from mail.profihost.ag (mail.profihost.ag [85.158.179.208]) by cuda.sgi.com with ESMTP id 9qGBChsp0ZEhqDN1 (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 14 Aug 2012 23:31:21 -0700 (PDT) Message-ID: <502B4232.7090308@profihost.ag> Date: Wed, 15 Aug 2012 08:31:14 +0200 From: Stefan Priebe - Profihost AG MIME-Version: 1.0 Subject: Re: aborted SCSI commands while discarding/unmapping via mkfs.xfs References: <502AB82D.9090408@profihost.ag> <20120814213535.GK2877@dastard> In-Reply-To: <20120814213535.GK2877@dastard> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: dchinner@redhat.com, Christoph Hellwig , Ronnie Sahlberg , "xfs@oss.sgi.com" Am 14.08.2012 23:35, schrieb Dave Chinner: > On Tue, Aug 14, 2012 at 10:42:21PM +0200, Stefan Priebe wrote: >> Hello list, >> >> i'm testing KVM with qemu, libiscsi, virtio-scsi-pci and >> scsi-general on top of a nexenta storage solution. While doing >> mkfs.xfs on an already used LUN / block device i discovered that the >> unmapping / discard commands mkfs.xfs sends take a long time which >> results in a lot of aborted scsi commands. > > Sounds like a problem with your storage being really slow at > discards. > >> Would it make sense to let mkfs.xfs send these unmapping commands in >> small portations (f.e. 100MB) > > No, because the underlying implementation (blkdev_issue_discard()) > already breaks the discard request up into the granularity that is > supported by the underlying storage..... > >> or is there another problem in the >> patch to the block device? Any suggestions or ideas? > > .... which, of course, had bugs in it so is a muchmore likely cause > of your problems. > > That said,the discard granularity is derived from information the > storage supplies the kernel in it's SCSI mode page, so if the > discard granularity is too large, that's a storage problem, not a > linux problem at all, let alone a mkfs.xfs problem. Thanks for this excelent explanation. Stefan _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs