IDE write speed (Promise versus AMD)

[Jan Kasprzak <kas@informatics.muni.cz>]

	Hello, all!

	I have a machine with six identical IDE drives (WD1200BB),
three of them connected to the on-board controller (it is AMD 768MPX chipset),
and other three are connected to the Promise controller (PDC 20269).
All drives are UDMA 100, read speed measured by "hdparm -t /dev/hd[abcefg]"
is about 45 MBytes/s for every drive. However, the write speed seems
to differ between AMD and Promise controllers. I've tried to do

time sh -c 'dd if=/dev/zero of=/dev/hdX bs=1024k count=2048; sync'

- it takes about 50 seconds (~40 MByte/s write speed) on hda, hdb and hdc,
but 2 minutes 48 seconds (~12 MByte/s write speed) on hde, hdf and hdg.
I have 1 GB of RAM, server is dual athlon 2000+. Kernel is 2.4.20-pre5-ac1.

	Is there any problem with the Promise IDE driver on Linux?

	Thanks,

-Yenya

-- 
| Jan "Yenya" Kasprzak  <kas at {fi.muni.cz - work | yenya.net - private}> |
| GPG: ID 1024/D3498839      Fingerprint 0D99A7FB206605D7 8B35FCDE05B18A5E |
| http://www.fi.muni.cz/~kas/   Czech Linux Homepage: http://www.linux.cz/ |
       Pruning my incoming mailbox after being 10 days off-line,
       sorry for the delayed reply.