HD DMA settings

[Ed Schernau <ed schernau com>]

Hello all,

I have Liunx 2.4.17 with a Promise FastTrak TX2, and 2 WD 40GB ATA100 disks 
in a RAID0 stripe set.  It works wonderfully - "modprobe pdcraid" and Linux 
sees them no problem.  I used Linux FDISK to make the partitions, and can see
all partitions from both Linux and Win2000 (dual boot, from separate disk).

/dev/hde never gets programmed for DMA, multicount, and both disks were in 
mode "68" which is not ATA-100 speed.  I get some "drive not ready errors" in 
/var/log/messages, but my data is fine (weird!).  Manually setting the speed 
settings with hdparm like so:

hdparm -m16 -d1 -X69 /dev/hde, and
hdparm -X69 /dev/hdg makes them identical from a /proc/ide/hd[e,g]/settings 
perspective.  

Simply turning on DMA for /dev/hde makes the error messages go away.

Three questions:
Any ideas why this does not automatically get set at boot?
Also, any idea why each drive shows a radically different CHS geometry?
What does "CANNOT DECODE HOST" mean in the /proc/ide/pdc202xx file?

Ed

PS For the curious, tiobench data:

[Ed tempinstall tiotest-0.26]$ ./tiobench.pl --size 1024 --dir /mnt/raid/test
Size is MB, BlkSz is Bytes, Read and Write are MB/sec, Seeks are Seeks/sec

 Dir   Size   BlkSz  Thr#  Read (CPU%)   Write (CPU%)   Seeks (CPU%)
----- ------ ------- ---- ------------- -------------- --------------
/mnt/  1024   4096    1   44.2241 26.0% 39.2536 34.3%  152.126 1.29%
/mnt/  1024   4096    2   29.9385 18.6% 38.0826 33.3%  178.977 1.23%
/mnt/  1024   4096    4   29.5640 19.2% 38.6084 33.9%  198.879 1.29%
/mnt/  1024   4096    8   27.6160 17.9% 38.4465 34.0%  213.668 1.33%