From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id n4JEBQXj047818 for ; Tue, 19 May 2009 09:11:26 -0500 Received: from concorde.pha.jhu.edu (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 9476C296F49 for ; Tue, 19 May 2009 07:11:36 -0700 (PDT) Received: from concorde.pha.jhu.edu (concorde.pha.jhu.edu [128.220.143.18]) by cuda.sgi.com with ESMTP id ALxFjz3KImEACiVW for ; Tue, 19 May 2009 07:11:36 -0700 (PDT) Received: from [128.220.233.109] (cue.pha.jhu.edu [128.220.233.109]) (authenticated bits=0) by concorde.pha.jhu.edu (8.13.1/8.13.1) with ESMTP id n4JEBXTu014659 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 19 May 2009 10:11:34 -0400 Message-ID: <4A12BE15.3080908@pha.jhu.edu> Date: Tue, 19 May 2009 10:11:33 -0400 From: Josh Greenberg MIME-Version: 1.0 Subject: question on agcount and agsize 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: xfs@oss.sgi.com I've just installed xfs for the first time and I'm trying to put an xfs file system on a large disk. When I just tried with no arguments, it told me that the agsize was too large and the maximum is 268435455 blocks. I wasn't familiar with allocation groups at all so I researched this a little bit. I found out what an allocation group is but there aren't many recommendations on agcount other than "don't make it too big" because it slows the disk down as it gets full. However, after playing with the numbers, I found that the lowest number it will accept for agcount is 44. I now have a file system with the following structure: meta-data=/dev/md0 isize=256 agcount=44, agsize=266361205 blks = sectsz=512 data = bsize=4096 blocks=11719892992, imaxpct=25 = sunit=0 swidth=0 blks, unwritten=1 naming =version 2 bsize=4096 log =internal log bsize=4096 blocks=32768, version=1 = sectsz=512 sunit=0 blks realtime =none extsz=65536 blocks=0, rtextents=0 I have two questions: 1. Does the agcount have to be a power of 2? Almost every example of agcount I've seen online has been a power of 2 (2, 4, 8, 16, and 32). I originally tried an agcount of 64 which worked but then tried to size it down so it wasn't too large. Will this cause problems later. 2. Is 44 too large? Will I experience a slow down as the disk fills? I've seen people recommend that you not go over agcount=32 and even someone who said not to exceed agcount=8. What are the long term ramifications of this? Thanks, Josh _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs