From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Zhang Subject: RE: raid0 low performance Date: Fri, 01 Jul 2005 10:42:51 -0400 Message-ID: <1120228971.5501.19.camel@localhost.localdomain> References: <200507011255.j61CtXp10224@www.watkins-home.com> <1120223833.5507.40.camel@localhost.localdomain> Reply-To: mingz@ele.uri.edu Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-8UrDc5ueUn63GcKa4fCu" Return-path: In-Reply-To: <1120223833.5507.40.camel@localhost.localdomain> Sender: linux-raid-owner@vger.kernel.org To: Guy Cc: 'Linux RAID' List-Id: linux-raid.ids --=-8UrDc5ueUn63GcKa4fCu Content-Type: text/plain Content-Transfer-Encoding: quoted-printable i wrote another program to read from device and then discard. ./synctest /dev/md1 Personalities : [linear] [raid0] [raid1] [raid5] [multipath] read_ahead 1024 sectors md1 : active raid0 sdl[3] sdk[2] sdb[1] sda[0] 1562845184 blocks 64k chunks unused devices: 1048576Bytes * 1024 : 158.459MB/s 524288Bytes * 2048 : 164.935MB/s 262144Bytes * 4096 : 173.649MB/s 131072Bytes * 8192 : 174.228MB/s 65536Bytes * 16384 : 178.462MB/s 32768Bytes * 32768 : 177.569MB/s 16384Bytes * 65536 : 177.888MB/s 8192Bytes * 65536 : 173.809MB/s 4096Bytes * 131072 : 172.732MB/s 2048Bytes * 131072 : 165.512MB/s 1024Bytes * 131072 : 150.354MB/s so looks like the bus is not a bottleneck here. and read ahead really works here. i guess the problem is r/w disparity in controller or driver. thanks guys ming On Fri, 2005-07-01 at 09:17 -0400, Ming Zhang wrote: > On Fri, 2005-07-01 at 08:55 -0400, Guy wrote: > > I think you should test 2 or more disks at the same time. This > would prove > > that your system can or can't move more than about 60MB/s. >=20 >=20 > i tested and seems that 90MB/s is the max here. >=20 >=20 > if i run 2 program copy on 2 disks independently on same card, both of > them bound at 45MB/s > if i run 3 program copy on 3 disks independently on same card, both of > them bound at 27 or 28MB/s so total is still 90MB/s > if i run 2 program copy on 2 disks but one is on 4 port marvel and > another is 8 port marvel, then both of the bound at 55MB/s which is > disk > limitation. >=20 > so i guess the card or bus has problem. i will check bus speed soon. >=20 >=20 --=-8UrDc5ueUn63GcKa4fCu Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) iD8DBQBCxVZrSYbkL5BnVYoRAnCfAJ0Y7w2X3ISBV1vjjSeJO/3mhdJBggCbB7Ye 6uODVNOY9f6plFbf7dGcwEE= =eHNp -----END PGP SIGNATURE----- --=-8UrDc5ueUn63GcKa4fCu--