In article <14311.21721.838556.473924@scree.melog.de>,
	Hauke Fath <hf@melog.de> writes:
> where sd2 is a brand new 9G disk. Why is it attached with only 10 MHz
> transfer rate?

It must be a configuration problem because it works in general:

ahc0: target 0 using 16Bit transfers
ahc0: target 0 synchronous at 20.0MHz, offset = 0x8
sd0 at scsibus0 targ 0 lun 0: <IBM, DDRS-39130W, S97B> SCSI2 0/direct fixed
sd0: 8715 MB, 8387 cyl, 10 head, 212 sec, 512 bytes/sect x 17850000 sectors

> (The AHA 2940UW has its "ultra" option activated).

Update to the newest BIOS and double check if says "40MHz" for that device.

> The three disks hang off the wide channel, and there are a CDROM and a 
> Tandberg SLR5 on the narrow channel.

It could be related to the other device not being aware of Ultra SCSI.
In my case the IBM disk is the only device attached to that bus.

-- 
Matthias Scheler                            http://www.sighardstrasse.de/~tron/