From owner-freebsd-stable@FreeBSD.ORG Sun Mar 30 08:00:13 2003 Return-Path: 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 AD0F537B415 for ; Sun, 30 Mar 2003 08:00:13 -0800 (PST) Received: from mailbox.univie.ac.at (mail.univie.ac.at [131.130.1.27]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7850A43F85 for ; Sun, 30 Mar 2003 08:00:12 -0800 (PST) (envelope-from l.ertl@univie.ac.at) Received: from adslle.cc.univie.ac.at (adslle.cc.univie.ac.at [131.130.102.11]) by mailbox.univie.ac.at (8.12.2/8.12.2) with ESMTP id h2UG01jW010072; Sun, 30 Mar 2003 18:00:04 +0200 Date: Sun, 30 Mar 2003 18:00:01 +0200 (CEST) From: Lukas Ertl To: Chuck Swiger In-Reply-To: <3E870CC7.5000204@mac.com> Message-ID: <20030330175605.E23911@leelou.in.tern> References: <20030330125138.K23911@leelou.in.tern> <3E870CC7.5000204@mac.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE X-DCC-ZID-Univie-mailbox-Metrics: mailbox 4251; Body=2 Fuz1=2 Fuz2=2 cc: freebsd-stable@freebsd.org Subject: Re: vinum performance X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Mar 2003 16:00:16 -0000 On Sun, 30 Mar 2003, Chuck Swiger wrote: > Lukas Ertl wrote: > [ ... ] > > I created several RAID 0 and RAID 5 volumes with different stripe sizes > > and let bonnie++ run over the filesystems. I was quite disappointed abo= ut > > the RAID 5 performance, and even the RAID 0 performance wasn't too good > > (a plain single disk filesystem was almost as fast as or even faster th= an > > a RAID 0 stripe, and I wouldn't expect that). > > > > RAID 5 performance was really a mess, some of the test took more than > > 30min. to complete. > > There are three goals or priorities to choose from when configuring > RAID: performance, reliability, and cost. What are yours? I just wanted to test the performance of these drives and of vinum; I had no goals to reach. > Also, what tasks you intend to use the RAID filesystem for are critical > to consider, even if the answer is simply "undifferentiated > general-purpose storage". In particular, RAID-5 write performance is > going to be slow, even with RAID hardware support which offloads the > parity calculations from the system CPU(s). RAID-5 is best suited for > read-mostly or read-only volumes, where you value cost more than > performance. Ok. But I still don't understand why RAID 5 write performance is _so_ bad. The CPU is not the bottle neck, it's rather bored. And I don't understand why RAID 0 doesn't give a big boost at all. Is the ahc driver known to be slow? > Um, that is a dual-channel card, and you're splitting drives onto both > channels, right? Yes, it is dual channel, but the disks I'm testing are all connected to the same channel. Bad layout? regards, le --=20 Lukas Ertl eMail: l.ertl@univie.ac.at UNIX-Systemadministrator Tel.: (+43 1) 4277-14073 Zentraler Informatikdienst (ZID) Fax.: (+43 1) 4277-9140 der Universit=E4t Wien http://mailbox.univie.ac.at/~le/