From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Scobie Subject: Re: Poor RAID5 performance on new SMP system Date: Tue, 19 Oct 2004 07:41:53 +1300 Sender: linux-raid-owner@vger.kernel.org Message-ID: <41740E71.4090907@sauce.co.nz> References: <20041018015803.M50347@liquid-nexus.net> <41733C14.8020000@sauce.co.nz> <20041018172202.M60005@liquid-nexus.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20041018172202.M60005@liquid-nexus.net> To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Marc Marais wrote: > I've moved one of the IDE cards to the 64 bit bus and thats improved things a > lot. The 2nd card isnt 3.3v capable and won't go into the 64 bit slot though > so I'm going to replace it. > > I noticed using vmstat that the average latency (await) is over 50ms for the > card on the secondary PCI bus and less than 20ms on the 64 bit bus... Very > interesting... Glad it's not going to be a total loss. I find AMD's behaviour over this bug to be very disappointing - motherboards using this broken south bridge can still be purchased today and the box does not state "Secondary PCI bus throughput limited to +- 25MB/s". You will not find this problem mentioned on their website either. The board I tested is only 9 months old and when I pulled the SCSI card and discs and placed them on the 33MHz bus of an equivalent dual Xeon board, the throughput went up to +-90MB/s. I was a big AMD fan prior to this, as the bang for the buck is way better, but the time, money and effort wasted left a bad taste. Regards, Richard