From owner-freebsd-questions@FreeBSD.ORG Fri Sep 29 15:53:24 2006 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 E8FB616A403 for ; Fri, 29 Sep 2006 15:53:24 +0000 (UTC) (envelope-from snagit@cbpratt.prohosting.com) Received: from n120.sc0.cp.net (smtpout1107.sc0.he.tucows.com [64.97.144.107]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5AD3843D64 for ; Fri, 29 Sep 2006 15:53:24 +0000 (GMT) (envelope-from snagit@cbpratt.prohosting.com) Received: from [192.168.1.100] (67.47.213.85) by n120.sc0.cp.net (7.2.069.1) (authenticated as eagletree@hughes.net) id 451CC1560001482D for freebsd-questions@freebsd.org; Fri, 29 Sep 2006 15:53:06 +0000 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Transfer-Encoding: 7bit Message-Id: Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed To: FreeBSD Questions From: Chris Date: Fri, 29 Sep 2006 08:52:58 -0700 X-Mailer: Apple Mail (2.752.2) Subject: Swap Size Importance? 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, 29 Sep 2006 15:53:25 -0000 As a standard practice, I've always configured swap file to be double the size of real ram split across system and data disk. For example, 8gb on da0 and 8gb on da1 if the system has 8g real ram. In practice, In 7 or 8 years, I've never seen swap used for anything but a few k of inactive processes and I would imagine if real active process swapping occurred, it would be an immediate indicator that the system that isn't responsive enough for use anymore and requires upgrade or tuning. Can't run a website process off disk and keep anyone coming to the site ;-). (BTW, I'm talking only about high end servers, not test boxes where I've seen lots of swapping). I'm at the point of attempting my first gvinum software raid-5 and realized, I need the entire disk storage of all three non-system drives to avoid pulling an 8gb chunk out of the drive sizes. The configuration is one scsi 72g system disk and 3 that will be used for the raid volume. I should mention I turn off dumps, haven't found the use for that in a production server since it should not be rebooting or it's back in the shop and another box is taking it's place. Is there any shortfall in performance or reliability to running production with swap equal in size to the 8gb of system memory? I can't think of any but don't want to make a hard to correct mistake once this thing goes in.