From owner-freebsd-questions@FreeBSD.ORG Fri Dec 16 13:38:45 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DC58C16A41F for ; Fri, 16 Dec 2005 13:38:45 +0000 (GMT) (envelope-from xfb52@dial.pipex.com) Received: from smtp-out6.blueyonder.co.uk (smtp-out6.blueyonder.co.uk [195.188.213.9]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9587D43D66 for ; Fri, 16 Dec 2005 13:38:40 +0000 (GMT) (envelope-from xfb52@dial.pipex.com) Received: from [192.168.0.2] ([82.41.253.189]) by smtp-out6.blueyonder.co.uk with Microsoft SMTPSVC(5.0.2195.6713); Fri, 16 Dec 2005 13:39:35 +0000 Message-ID: <43A2C35E.9060206@dial.pipex.com> Date: Fri, 16 Dec 2005 13:38:38 +0000 From: Alex Zbyslaw User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-GB; rv:1.7.12) Gecko/20051106 X-Accept-Language: en MIME-Version: 1.0 To: freebsd-questions@freebsd.org References: <20051216123357.4932.qmail@web31611.mail.mud.yahoo.com> <20051216131451.GV2413@merkur.atekomi.net> In-Reply-To: <20051216131451.GV2413@merkur.atekomi.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 16 Dec 2005 13:39:35.0163 (UTC) FILETIME=[26FBA4B0:01C60246] Subject: Re: swap - 2 HDs X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Dec 2005 13:38:46 -0000 Will Maier wrote: >On Fri, Dec 16, 2005 at 09:33:57AM -0300, Aguiar Magalhaes wrote: > > >>Is It recommended to configure swap area in both HDs ?? >> >> > >I don't see the point -- swap is where pages that don't fit in your >real memory go. It's less optimal than real memory in terms of >latency, but I don't see how two disks would make swap performance >much better. > > This is contrary to the "usual" advice which is to split swap across disks AFAIK. I've never done any benchmarks, but my gut feeling would be that if the disks were on separate controllers, and if the machine did swap regularly then two swap partitions would be beneficial. Even on the same controller it could easily make a difference since individual IDE/SATA disks can't actually reach the performance of the channel as a whole. Given that these are large hard disks, what's 2 or 4Gb in the grand scheme? A drop in the ocean, so I would (and do) put swap on both. Of course, if the machine actually swaps regularly then investing in more RAM would give the best performance! --Alex PS If the two disks are larger than your actual needs, then you might want to consider emergency scenarios like one of your disks dieing. If, for example, you put a spare, bootable version of FreeBSD on the 2nd disk to aid recovery then that OS will need a swap partition anyway and you might as well use it regularly. $0.02