Messages in this thread |  | | Date | Thu, 15 Nov 2001 17:22:46 +0100 | From | Jens Axboe <> | Subject | Re: Linux i/o tweaking |
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On Thu, Nov 15 2001, Roy Sigurd Karlsbakk wrote: > Hi all > > After three days at Compaq's lab in Oslo, testing their medium-level > servers and storage systems with Linux, I've come to some sort of > conclusions, although these may be wrong. I also have come over a few > problems that I couln't find a good solution to. > > * When running RAID from a Compaq Smart 5302/64 controller, software > RAID-5 is (slightly - ~15%) faster (on JBOD - each disk is configured as > a RAID-0 device with max - 256kB - stripe size) than the > hardware/controller based RAID-5. Both CPUs (1266MHz/512kB cache) are > maxed out by reading from software RAID-5 (???), giving me >= 107MB/s on > two SCSI-3 buses with six disks on each bus. > > * Even though I can get up to 25 MB/s from each disk, I can't get more > than 107 MB/s on the whole bunch (12 drives). It doesn't help much to do > RAID-0 either. Don't understand anything ...
Could you please try and profile where the time is spent? Boot with profile=2, and then do
# readprofile -r # do I/O testing # readprofile | sort -nr
-- Jens Axboe
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