From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: strange performance of raid0 Date: Sun, 15 Feb 2004 11:04:32 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <20040215100432.GA19002@rap.rap.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi I have some strange performance results on a raid0 I have 4 IDE disks on two controllers, the one on the motherboard of the duron 1 GHz mackine, the other a promise TX2 plus SATA + PATA controller. I run kernel 2.4.22 The disks and hdparm -t on each of them /dev/hdc1 seagate 80 GB 16 MB/s /dev/sda1 maxtor sata 200 GB 50 MB/s /dev/sdb7 maxtor 160 GB 54 MB/s The partitions are al about 5 GB each. If I make a raid0 device of all of them I get a thruput of 45 MB/s IIf I exclude the hdc1 partition, I get around 75 MB/s. The system is a little loaded - but that would be normal operating conditions. CPU is 90 % idle. I have about 100 MB free RAM. Why is it slower with 3 disks in the raid0 than 2 disks? Why don't I get approx 100 MB/s out of just the two? Best regards Keld