From owner-freebsd-stable Wed Nov 8 16:58:34 2000 Delivered-To: freebsd-stable@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id E4BE237B479 for ; Wed, 8 Nov 2000 16:58:30 -0800 (PST) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id eA90wUD02311; Wed, 8 Nov 2000 16:58:30 -0800 (PST) Date: Wed, 8 Nov 2000 16:58:30 -0800 From: Alfred Perlstein To: Brian Behlendorf Cc: stable@FreeBSD.ORG Subject: Re: disk I/O Message-ID: <20001108165829.F5112@fw.wintelcom.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i In-Reply-To: ; from brian@collab.net on Wed, Nov 08, 2000 at 04:35:13PM -0800 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG * Brian Behlendorf [001108 16:35] wrote: > > RELENG_4, kernel last updated & built Aug 31st, so apologies if this > touches a problem that was fixed since then. I'd be happy to upgrade > after 4.2-RELEASE goes out if people think there was a fix applied > for this. > > I'm having agonizingly slow disk I/O. Granted, this is a heavily pounded > machine (~2M web hits/day with ~50K being CGI or java, 500K mail > deliveries using qmail, lots of CVS accesses) yet I get spikes in the load > going up to 200 at times, during which the machine's largely frozen to > shell access & other services are much slower. It always comes back (go > freebsd!) but it still feels like I/O is the culprit. The CPU almost > always has idle time available, yet during the day even doing an "ls" in a > moderately sized dir is slow. Here's iostat 5: You have an IO problem that leads to a cascade failure, basically everything starts piling up on the disks, because it's a multiuser machine you're most likley having a lot of sparse access to the drives so unlike your home machine you're probably doing a lot more seeking which is killing performance. I'd get a hardware raid system, they're a lifesaver for IO and reliability. best of luck, -Alfred To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message