From owner-freebsd-fs@FreeBSD.ORG Sat May 23 13:26:46 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 175451065673 for ; Sat, 23 May 2009 13:26:46 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from mx.egr.msu.edu (surfnturf.egr.msu.edu [35.9.37.164]) by mx1.freebsd.org (Postfix) with ESMTP id E1B468FC1B for ; Sat, 23 May 2009 13:26:45 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from localhost (localhost [127.0.0.1]) by mx.egr.msu.edu (Postfix) with ESMTP id 43B8071F189; Sat, 23 May 2009 09:26:45 -0400 (EDT) X-Virus-Scanned: amavisd-new at egr.msu.edu Received: from mx.egr.msu.edu ([127.0.0.1]) by localhost (surfnturf.egr.msu.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DcjjJ1t0JE21; Sat, 23 May 2009 09:26:45 -0400 (EDT) Received: from localhost (daemon.egr.msu.edu [35.9.44.65]) by mx.egr.msu.edu (Postfix) with ESMTP id 1396271F172; Sat, 23 May 2009 09:26:45 -0400 (EDT) Received: by localhost (Postfix, from userid 21281) id 106D0712; Sat, 23 May 2009 09:26:45 -0400 (EDT) Date: Sat, 23 May 2009 09:26:45 -0400 From: Adam McDougall To: Randy Bush Message-ID: <20090523132644.GN35763@egr.msu.edu> References: <9e20d71e0905230537ibcaf852g1dc32b6ffc3a681d@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) Cc: freebsd-fs , Artis Caune Subject: Re: raidz2 a bit big X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 May 2009 13:26:46 -0000 On Sat, May 23, 2009 at 06:04:04AM -0700, Randy Bush wrote: >> NAME STATE READ WRITE CKSUM >> tank ONLINE 0 0 0 >> raidz2 ONLINE 0 0 0 >> da0s3 ONLINE 0 0 0 >> da1s3 ONLINE 0 0 0 >> da2s1 ONLINE 0 0 0 >> da3s1 ONLINE 0 0 0 >> da4s1 ONLINE 0 0 0 >> da5s1 ONLINE 0 0 0 >> da6s1 ONLINE 0 0 0 >> da7s1 ONLINE 0 0 0 >> da8s1 ONLINE 0 0 0 >> da9s1 ONLINE 0 0 0 >> da10s1 ONLINE 0 0 0 >> da11s1 ONLINE 0 0 0 > > Reads on such configurations are very slow. how are writes? > If one of your disk, for example, is capable of 100 IO per/sec, then: > with 12 disks in one raidz2 vdev you get only 100 IOPS > with 4 disks in raidz2 (total 3 raidz2 vdevs) you get 300 IOPS > with 2 disks in mirror (total 6 mirror vdevs) you can get 1200 IOPS ok. sounds nice. but then, don't i have six file systems and have to start playing lay-out design games? randy For an example: (btw the read speed is fantastic in a mirror and the write is notably faster than raidz, but if your I/O is all going to go through a gig nic, then it may not matter such as if you are just using it for a low concurrent user stash of large files) zpool create tank mirror aacd0s1d aacd1s1d mirror aacd2s1d aacd3s1d mirror aacd4s1d aacd5s1d mirror aacd6s1d aacd7s1d # zpool status pool: tank state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM tank ONLINE 0 0 0 mirror ONLINE 0 0 0 aacd0s1d ONLINE 0 0 0 aacd1s1d ONLINE 0 0 0 mirror ONLINE 0 0 0 aacd2s1d ONLINE 0 0 0 aacd3s1d ONLINE 0 0 0 mirror ONLINE 0 0 0 aacd4s1d ONLINE 0 0 0 aacd5s1d ONLINE 0 0 0 mirror ONLINE 0 0 0 aacd6s1d ONLINE 0 0 0 aacd7s1d ONLINE 0 0 0