From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 1A5797F4E for ; Wed, 25 Sep 2013 16:18:31 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay3.corp.sgi.com (Postfix) with ESMTP id B1AFFAC001 for ; Wed, 25 Sep 2013 14:18:27 -0700 (PDT) Received: from greer.hardwarefreak.com (mo-65-41-216-221.sta.embarqhsd.net [65.41.216.221]) by cuda.sgi.com with ESMTP id ND2sMUA1q2g7jC2l for ; Wed, 25 Sep 2013 14:18:26 -0700 (PDT) Message-ID: <52435327.9080607@hardwarefreak.com> Date: Wed, 25 Sep 2013 16:18:31 -0500 From: Stan Hoeppner MIME-Version: 1.0 Subject: Re: xfs hardware RAID alignment over linear lvm References: In-Reply-To: Reply-To: stan@hardwarefreak.com List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Stewart Webb Cc: xfs@oss.sgi.com On 9/25/2013 7:56 AM, Stewart Webb wrote: > Hi All, Hi Stewart, > I am trying to do the following: > 3 x Hardware RAID Cards each with a raid 6 volume of 12 disks presented to > the OS > all raid units have a "stripe size" of 512 KB Just for future reference so you're using correct terminology, a value of 512KB is surely your XFS su value, also called a "strip" in LSI terminology, or a "chunk" in Linux software md/RAID terminology. This is the amount of data written to each data spindle (excluding parity) in the array. "Stripe size" is a synonym of XFS sw, which is su * #disks. This is the amount of data written across the full RAID stripe (excluding parity). > so given the info on the xfs.org wiki - I sould give each filesystem a > sunit of 512 KB and a swidth of 10 (because RAID 6 has 2 parity disks) Partially correct. If you format each /dev/[device] presented by the RAID controller with an XFS filesystem, 3 filesystems total, then your values above are correct. EXCEPT you must use the su/sw parameters in mkfs.xfs if using BYTE values. See mkfs.xfs(8) > all well and good > > But - I would like to use Linear LVM to bring all 3 cards into 1 logical > volume - > here is where my question crops up: > Does this effect how I need to align the filesystem? In the case of a concatenation, which is what LVM linear is, you should use an XFS alignment identical to that for a single array as above. -- Stan _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs