From owner-freebsd-stable@FreeBSD.ORG Mon Oct 17 00:01:24 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 0605216A41F for ; Mon, 17 Oct 2005 00:01:24 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9FC1C43D46 for ; Mon, 17 Oct 2005 00:01:23 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.13.1/8.13.3) id j9H01MMr066276; Sun, 16 Oct 2005 19:01:22 -0500 (CDT) (envelope-from dan) Date: Sun, 16 Oct 2005 19:01:22 -0500 From: Dan Nelson To: Will Saxon Message-ID: <20051017000122.GF21223@dan.emsphone.com> References: <0E972CEE334BFE4291CD07E056C76ED807738005@bragi.housing.ufl.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0E972CEE334BFE4291CD07E056C76ED807738005@bragi.housing.ufl.edu> X-OS: FreeBSD 5.4-STABLE X-message-flag: Outlook Error User-Agent: Mutt/1.5.11 Cc: stable@freebsd.org 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: Mon, 17 Oct 2005 00:01:24 -0000 In the last episode (Oct 16), Will Saxon said: > I am trying to diagnose a problem whereby a virus scanner (clam > antivirus) is taking too long to scan attachments on a mail server. > We have an attachment limitation of 20MB and an attachment of 7-20MB > can take over 3 minutes to scan. This often causes the sending mail > server to timeout and resend the mail. > > In this case, my mail gateway is is a dual 3.06GHz Xeon with 1GB of > ram and 2 36GB 15krpm drives in a raid-1 on a smart array 6i (cciss) > controller. I am running FreeBSD 5.4-RELEASE-p1. > > Systat -vmstat reports the disk mirror is 100% busy at all times on > this machine, with an average of around 300 tps at 15KB/t. This seems > wrong to me, as these numbers are maintained even when the system > doesn't otherwise appear busy. We don't seem to be swamped by log > writes. How can I tell what's generating these disk writes? At the > moment the 100% disk utilization is the only thing I can see that > would cause the scanning delay. The machine overall is sluggish with > file operations. Are you swapping? Check either "vmstat 1" or top output. You can also tell top to display blocking I/O requests per process by hitting "m", then ask it to sort by I/O by hitting "ototal". -- Dan Nelson dnelson@allantgroup.com