From owner-freebsd-performance@FreeBSD.ORG Tue Oct 19 20:52:26 2004 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E0D9C16A4CE for ; Tue, 19 Oct 2004 20:52:26 +0000 (GMT) Received: from mail.geeks.org (jacobs.Geeks.ORG [204.153.247.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7536143D31 for ; Tue, 19 Oct 2004 20:52:26 +0000 (GMT) (envelope-from drechsau@Geeks.ORG) Received: by mail.geeks.org (Postfix, from userid 400) id 49C3B20B59; Tue, 19 Oct 2004 15:52:25 -0500 (CDT) Date: Tue, 19 Oct 2004 15:52:25 -0500 From: Mike Horwath To: =?iso-8859-1?B?Sm/jb19DYXJsb3NfTWVuZGVzX0x17XM=?= Message-ID: <20041019205225.GB39270@octanews.net> References: <20041019193501.GC78974@cybernetik.net> <41756EBF.3010008@jonny.eng.br> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <41756EBF.3010008@jonny.eng.br> X-PGP-Fingerprint: D8 24 CC E6 47 5F E4 60 BF B7 6E FA BF C7 6E C5 X-GPG-Fingerprint: 6A89 E78A B8B1 69D9 8CDB E966 4A5A C3F9 A1B0 C381 User-Agent: Mutt/1.5.6i cc: Kristofer Pettijohn cc: freebsd-performance@freebsd.org Subject: Re: Disk I/O Performance X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Oct 2004 20:52:27 -0000 On Tue, Oct 19, 2004 at 04:45:03PM -0300, João_Carlos_Mendes_Luís wrote: > I'd say that you have to check which CCD chunk size is best for > your needs. The manual for vinum recommends avoiding chunk sized to a > power of two, which is probably the first big mistake of everybody. > > Try mounting with option noatime, if you haven't already. And use > the largest block size possible when formatting. Last time I read about > there was a limit of 16384, but I would expect better performance for > large file with 64k blocks (and 8k frags). > > If you don't have a need for safety on the files, you could try > mount async and measure if it suits better you need for performance than > softupdates. Sometimes softupdates is faster, and it is always safer. All good ideas except the issue is bandwidth performance across the disks. I am seeing the same thing (and Kristofer and I have been working together, kinda, on this). It is as if I/O is being preferred for writing vs reading, very weird. His 5 disk stripe (well, it used to be five when I managed the machine) should not have issues, but this recently begun happening both on his systems and some of mine. Very odd stuff... -- Mike Horwath, reachable via drechsau@Geeks.ORG