From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Odd (slow) RAID performance Date: Thu, 30 Nov 2006 10:30:11 -0500 Message-ID: <456EF903.10502@tmr.com> References: <20061130143123.1E05912EDE@bluewhale.planbit.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20061130143123.1E05912EDE@bluewhale.planbit.co.uk> Sender: linux-raid-owner@vger.kernel.org To: Roger Lucas Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Roger Lucas wrote: >> -----Original Message----- >> From: linux-raid-owner@vger.kernel.org [mailto:linux-raid- >> owner@vger.kernel.org] On Behalf Of Bill Davidsen >> Sent: 30 November 2006 14:13 >> To: linux-raid@vger.kernel.org >> Subject: Odd (slow) RAID performance >> >> Pardon if you see this twice, I sent it last night and it never showed >> up... >> >> I was seeing some bad disk performance on a new install of Fedora Core >> 6, so I did some measurements of write speed, and it would appear that >> write performance is so slow it can't write my data as fast as it is >> generated :-( >> > > What drive configuration are you using (SCSI / ATA / SATA), what chipset is > providing the disk interface and what cpu are you running with? 3xSATA, Seagate 320 ST3320620AS, Intel 6600, ICH7 controller using the ata-piix driver, with drive cache set to write-back. It's not obvious to me why that matters, but if it helps you see the problem I''m glad to provide the info. I'm seeing ~50MB/s on the raw drive, and 3x that on plain stripes, so I'm assuming that either the RAID-5 code is not working well or I haven't set it up optimally. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979