Vladimir, In the part of the message that was quoted to the linux-raid list the performance of the RAID devices isn't specified. All I see is you testing /dev/sda1 and mentioning kernel modules, but no mention of /dev/mdX or /dev/YourVG/YourLV. What types of numbers are you seeing when using your RAID/LVM devices in your dd test? Also, you may want to try using bonnie++ to get some representative numbers as this program tends to be a little more representative of actual performance without involving the linux VM cache. I have yet to use 2.6 for RAID/LVM so I can't point you in a specific direction, however I didn't see any performance numbers for RAID or LVM devices. Try running bonnie++ or /dev/mdX or /dev/YourVG/YourLV and seeing if it's what you expect. Good luck, Andy. > -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx > [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of David Greaves > Sent: Thursday, August 19, 2004 11:53 AM > To: Vladimir I. Umnov > Cc: linux-raid@xxxxxxxxxxxxxxx > Subject: Re: Low perfomance of RAID0,RAID5, RAID+LVM on 2.6 > > -----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----- > > - > To unsubscribe from this list: send the line "unsubscribe > linux-raid" in the body of a message to > majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html > - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
