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 n6J0rpMD183696 for ; Sat, 18 Jul 2009 19:53:51 -0500 Received: from Ishtar.tlinx.org (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 64DA513AF8F7 for ; Sat, 18 Jul 2009 17:54:31 -0700 (PDT) Received: from Ishtar.tlinx.org (ishtar.tlinx.org [64.81.245.74]) by cuda.sgi.com with ESMTP id Ky9zKDOpTrvFo0SA for ; Sat, 18 Jul 2009 17:54:31 -0700 (PDT) Received: from [192.168.3.11] (Athena [192.168.3.11]) by Ishtar.tlinx.org (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id n6J0sTV5012906 for ; Sat, 18 Jul 2009 17:54:31 -0700 Message-ID: <4A626EC5.3090100@tlinx.org> Date: Sat, 18 Jul 2009 17:54:29 -0700 From: Linda Walsh MIME-Version: 1.0 Subject: data switchs su,sw and sunit,swidth 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: Linux-Xfs Resending this as I never saw it show up on the list (sent out yesterday) (while other the messages came back in under 15 minutes or so)... Have started to use RAID on a few of my disks and forgot about the xfs 'su*sw' and 'sunit*swidth' options. >>From what I get in reading the manpage, 'su' is used with 'sw' and 'sunit' is used with 'swidth'? The RAID controller in one of my machines uses a "strip element" size, expressed in bytes, allowed values seem to be limited to powers of 512*2^*[1..11] (512B up to 1MB) (though as previously noticed, although xfs's manpages claims to allow one expresses sizes with the unit 'm', it only permits .25m (256k), I guess I never tried seeing if the command line would take floating point ;^) ). I believe 'su' would be set to the 'strip element size' (in k or m). Then, for RAID 1 (mirror) would 'sw'==1? Would setting the su/sw value for a RAID 1 actually matter in any way? Ie, technically -- it would fill in numbers for OS book-keeping, but wouldn't change anything in terms of performance or layout, vs. 'physically' -- where it could change disk layout or performance? At RAID 0, I'd guess sw==2? In RAID 5, would it be sw == #Disks-1? So even w/6 disks, it still only uses 1 disk for parity and sw == 5? I wonder what becomes a max-safe RAID 5 size? (or is the number of parity disks a settable option with RAID 5?) Thanks!... Linda _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs