From owner-freebsd-questions@FreeBSD.ORG Tue May 19 05:06:44 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 02EE1106566B for ; Tue, 19 May 2009 05:06:44 +0000 (UTC) (envelope-from erikt@midgard.homeip.net) Received: from ch-smtp01.sth.basefarm.net (ch-smtp01.sth.basefarm.net [80.76.149.212]) by mx1.freebsd.org (Postfix) with ESMTP id 83A138FC14 for ; Tue, 19 May 2009 05:06:43 +0000 (UTC) (envelope-from erikt@midgard.homeip.net) Received: from c83-255-48-78.bredband.comhem.se ([83.255.48.78]:59604 helo=falcon.midgard.homeip.net) by ch-smtp01.sth.basefarm.net with esmtp (Exim 4.69) (envelope-from ) id 1M6HX6-0001oi-5y for freebsd-questions@freebsd.org; Tue, 19 May 2009 07:06:34 +0200 Received: (qmail 71384 invoked from network); 19 May 2009 07:06:30 +0200 Received: from owl.midgard.homeip.net (10.1.5.7) by falcon.midgard.homeip.net with ESMTP; 19 May 2009 07:06:30 +0200 Received: (qmail 17022 invoked by uid 1001); 19 May 2009 07:06:30 +0200 Date: Tue, 19 May 2009 07:06:30 +0200 From: Erik Trulsson To: Yuri Message-ID: <20090519050630.GA16959@owl.midgard.homeip.net> References: <4A00B3FA.5050905@rawbw.com> <4A11C53C.3090008@rawbw.com> <4ad871310905181337o6c368e14mccccf884f6839737@mail.gmail.com> <4A12225E.6000900@rawbw.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A12225E.6000900@rawbw.com> User-Agent: Mutt/1.5.19 (2009-01-05) X-Originating-IP: 83.255.48.78 X-Scan-Result: No virus found in message 1M6HX6-0001oi-5y. X-Scan-Signature: ch-smtp01.sth.basefarm.net 1M6HX6-0001oi-5y f8bc484d0d80b86ed027073dc70d70cd Cc: Glen Barber , freebsd-questions@freebsd.org Subject: Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 May 2009 05:06:44 -0000 On Mon, May 18, 2009 at 08:07:10PM -0700, Yuri wrote: > Glen Barber wrote: > > No, that is not reasonable (but in a perfect world, would be correct). > > > > You are limited by the bus speed and controller buffer speed > > (whichever is slower). > > > > > My motherboard has PCI Express v2.0, that is 500MB/s limitation. That's 500MB/s for each PCI-E 2.0 lane. The PCI-E lanes originating at your southbridge (Intel ICH10R) are only PCI-E 1.0 however for a max of 250MB/s per lane (in each direction.) This is irrelevant however since the built-in SATA controller is not attached to any PCI-E lanes. What is relevant is the connection between the northbridge and southbridge. In your case that connection is equivalent to a PCI-E x4 bus, for a max speed of 1GB/s (in each direction.) > Also it has HD/RAID controller Intel ICH10R Southbidge that has peak > SATA Data Rate 300MB/s. That's 300MB/s for each SATA channel. Unless you use a port-multiplier (which is poorly supported in FreeBSD) you will only have a single disk per SATA channel. > So this brings me to 300MB/s limit. > So 3X harddrives at 85MB/s will still scale. And 4X will already show > the limitation. Actually the buses involved sets the limit at 1GB/s (the Nortbridge-Southbridge connection.) There are likely to be other limits in play however such as the maximum throughput of the SATA controller, or the max load the CPU can sustain, or the transfer speed to RAM. Of these I suspect the controller itself will be the major bottleneck in your case closely followed by the CPU. Exactly how much they can support is not so easily predicted however - it will have to be measured. -- Erik Trulsson ertr1013@student.uu.se