Hi all !
I promised to show off RAID on a friend's box. Ok, so we set up
2.2.3 with corrosponding patches on his box with the following
hardware:
2 x IBM UltraStar 9ES 4.5 GB U2W
Adaptec 2940 UW
AMD K6 - 200 MHz
64 MB RAM
Each disk gives us around 11 MB/s using hdparm -t /dev/sd[ab]
If we run hdparm -t /dev/sda & hdparm -t /dev/sdb, (two hdparm's
concurrently) we get roughly 8.5 MB/s from each disk, a total of
17 MB/s.
This is the same number which I've seen on my own machine (dual PPro,
same controller, same disks), when running RAID-0. All as we would
have expected.
However, when we set up /dev/md0, a RAID-0 device between the two
disks, (in a configuration similar to what I've run myself), we get
around 10 MB/s from the md0 device. -- Less that we can get
from one single disk.
I guess it can't be the SCSI configuration/driver/bus/termination/etc.
because when we run two concurrent hdparm's on the disks, we get excellent
performance.
Also, I guess that it can't be the RAID configuration, because we tried
different chunk-sizes, and I read the HOWTO ;)
And finally, I guess it can't be the RAID drivers, because they have no
K6 specific code (from what I could see).
This boils down to; there is nothing wrong, but it still doesn't work
as we would have expected it to.
Does anyone have a clue about what could be going on ?? The main
difference between my own box which ran a similar configuration for long
time seems to be that this box is a K6. Anyone running raid0 on similar
configurations with a K6 CPU ?
Thanks,
--
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:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
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