From owner-freebsd-performance@FreeBSD.ORG Thu Oct 23 18:00:22 2008 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4DD95106569C for ; Thu, 23 Oct 2008 18:00:22 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout022.mac.com (asmtpout022.mac.com [17.148.16.97]) by mx1.freebsd.org (Postfix) with ESMTP id 3A7178FC1D for ; Thu, 23 Oct 2008 18:00:21 +0000 (UTC) (envelope-from cswiger@mac.com) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Received: from cswiger1.apple.com ([17.227.140.124]) by asmtp022.mac.com (Sun Java(tm) System Messaging Server 6.3-7.03 (built Aug 7 2008; 32bit)) with ESMTPSA id <0K97004VXDZLWP80@asmtp022.mac.com> for freebsd-performance@freebsd.org; Thu, 23 Oct 2008 10:59:46 -0700 (PDT) Message-id: From: Chuck Swiger To: Stephen Sanders In-reply-to: <4900B94B.5000108@softhammer.net> Date: Thu, 23 Oct 2008 10:59:45 -0700 References: <490097CC.9010802@opnet.com> <4900B94B.5000108@softhammer.net> X-Mailer: Apple Mail (2.929.2) Cc: freebsd-performance@freebsd.org Subject: Re: Disk Throughput test X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Oct 2008 18:00:22 -0000 On Oct 23, 2008, at 10:50 AM, Stephen Sanders wrote: > Good point about the RAID. It is set for RAID 5 as the data is > supposed > to be protected. RAID-10 provides somewhat better data protection, but less available space and better write performance especially for small writes. (For big writes, RAID-5 can do OK also, but small writes tend to really degrade RAID-5 performance, down to an order of magnitude *less* throughput compared with a single raw drive.) > Interestingly enough, diskinfo is telling me that the drive throughput > is 175MB/s. I'm guessing that this means diskinfo is a mixture of > reads > and writes? No, it should only be doing reads. For best-case read performance, it's likely to be at or near: dd if=_your_disks_ of=/dev/null bs=_raid_stripe_size_ ...or adjust bs up or down by factors of 2 and benchmark. Regards, -- -Chuck