From owner-freebsd-stable@FreeBSD.ORG Thu Nov 3 19:09:46 2005 Return-Path: X-Original-To: stable@freebsd.org Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7D0E516A41F for ; Thu, 3 Nov 2005 19:09:46 +0000 (GMT) (envelope-from brad@stop.mail-abuse.org) Received: from vhost109.his.com (vhost109.his.com [216.194.225.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1F0E943D45 for ; Thu, 3 Nov 2005 19:09:45 +0000 (GMT) (envelope-from brad@stop.mail-abuse.org) Received: from [10.0.1.210] (localhost.his.com [127.0.0.1]) by vhost109.his.com (8.12.11/8.12.3) with ESMTP id jA3J9g4n098423; Thu, 3 Nov 2005 14:09:43 -0500 (EST) (envelope-from brad@stop.mail-abuse.org) Mime-Version: 1.0 Message-Id: In-Reply-To: <20051103133248.Y60367@zoraida.natserv.net> References: <0E972CEE334BFE4291CD07E056C76ED807738005@bragi.housing.ufl.edu> <20051103133248.Y60367@zoraida.natserv.net> Date: Thu, 3 Nov 2005 19:53:13 +0200 To: Francisco From: Brad Knowles Content-Type: text/plain; charset="us-ascii" ; format="flowed" Cc: Brad Knowles , stable@freebsd.org, Will Saxon Subject: Re: Disk 100% busy X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Nov 2005 19:09:46 -0000 At 1:34 PM -0500 2005-11-03, Francisco wrote: > On Mon, 17 Oct 2005, Brad Knowles wrote: > >> Note that RAID-1 is the second worst-case for mail server performance -- >> it accelerates reads (if you have mirror load-balancing), but all writes >> are required to be held until complete on both disks. The only worse >> case would be RAID-5, where you have to write (or re-write) an entire >> RAID block at once, plus the parity information. > > Coming late into the thread... > What is a good raid level for a maildir IMAP server? RAID 10 (or 0+1 as > others call it). Yes, RAID 1+0 is generally considered to be the best. But keep in mind that you always want to stripe the mirrors and not mirror the stripes. If you do the former, then if one of the disks die then the mirror is broken but the stripe is still okay. If you do the latter, then if a disk dies then the stripe is broken, and then the mirror is also broken. -- Brad Knowles, "Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." -- Benjamin Franklin (1706-1790), reply of the Pennsylvania Assembly to the Governor, November 11, 1755 SAGE member since 1995. See for more info.