Quoting Joshua Baker-LePain <jlb17 at duke.edu>: > Wonderful. I'm testing RAID5 now, for which I had high hopes. Well, my guess is that there'll be fix for this by the time next kernel version is out. Obviously it is an bug that should be fixed. >> BTW, any particular reason not to use hardware RAID on 3ware? > > That was the initial plan. But I can't get anything even resembling > decent speeds out of them. These systems have 2 7500-8 boards in 'em > (on separate PCI buses). I had been running RH7.3 (!!) and XFS with > the boards in hardware RAID5 and a software RAID0 stripe across > those, and would get >100MB/s writes and >300MB/s reads. With > centos-4 and ext3, I was getting ~30MB/s writes and ~200MB/s reads. > The reads I'd be OK with, but the write speed is absurd. I tweaked > all I could think of, but nothing helped much. Yeah, mixing RAIDs like that sometimes can get you into trouble. I guess 3ware was not rebuilding anything while you were testing? Have you tested the speed of ext3 under RH7.3 (to rule out file system differences influencing your particular test)? Is the speed OK if you use hardware RAID-5 on one card on its own (not mixing it with sofware RAID-0 like you had under RH-7.3)? If it is, try this configuration instead. Create two hardware RAID-5 volumes (one on each card). Then use fdisk to mark them as Linux LVM (8e). Use pvcreate to create LVM physical volumes on them, put them into volume group (for example create a new one) and make a logical volume on them. Example: # pvcreate /dev/sda1 # pvcreate /dev/sdb1 # vgcreate -s 32m foobar /dev/sda1 /dev/sdb1 # vgdisplay foo # lvcreate -l nnn -n bar foo # mkfs.ext3 /dev/foo/bar # mount -t ext3 /dev/foo/bar /mnt Replace sda1 and sdb1 with actual partitions on RAID-5 volumes. Replace "nnn" in lvcreate with the number of free physical extents (PE) as shown by vgdisplay command. You can also test if striping will make any difference. For example, you might also replace the above lvcreate command with: # lvcreate -l nnn -i 2 -n bar foo /dev/sda1 /dev/sdb1 You can also give it -I (capital i) option to specify the stripe size, if you don't want to use default value. See "man lvcreate" for more info. ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.