From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: Low perfomance of RAID0,RAID5, RAID+LVM on 2.6 Date: Thu, 19 Aug 2004 16:53:25 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <4124CCF5.8010201@dgreaves.com> References: <20040819193200.27c97a4e@vovapc.kpml.int> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20040819193200.27c97a4e@vovapc.kpml.int> To: "Vladimir I. Umnov" Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Vladimir I. Umnov wrote: |HW: chipset 875WPE, P4 2.4HT, 3 SATA WD 160JD, 1 ATA Samsung 80Gb. |SW: kernel 2.6.6, libata drivers for PROMISE S150 TX4. |CONFIG: 256K readahead on all drives. | sda1,sdb1,sdc1->RAID0 (md0) | sda2,sdb2,sdc2,hda1->RAID5 (md1) | about 20 partitions on LVM2 with xfs,ext3,reiserfs | chunksize on md0, md1 = 256k - this was optimal with 2.6.0test3 about | year ago. | |Theoretically RAID0 read speed should be nearly read speed of one |drive multiply to number of drives, but I have: |dd if=/dev/sda1 of=/dev/null gives about 44 Mb/s on all drives (but on |sii3112 ide driver with WD 160JD about 55Mb/s and on libata the same |44) I use my arrays for large video files so large readahead is good. I use blockdev on the lvms: /sbin/blockdev --setra 4096 /dev/video_vg/video_lv /sbin/blockdev --setra 4096 /dev/video_vg/huge_lv the md device: /sbin/blockdev --setra 4096 /dev/md0 and the raw devices /sbin/blockdev --setra 4096 /dev/sda /sbin/blockdev --setra 4096 /dev/sdb /sbin/blockdev --setra 4096 /dev/sdc /sbin/blockdev --setra 4096 /dev/sdd /sbin/blockdev --setra 4096 /dev/hdb HTH David -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFBJMz08LvjTle4P1gRAkfpAJ9XA17vexSqmcN0LVFZOx0Dxik/BQCgjMk+ oAslumzTWosxF9WqnDXln3k= =C3uO -----END PGP SIGNATURE-----