At 21:52 27.09.99 +0000, Matthias Scheler wrote:
>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.

Is the Adaptec's BIOS flashable?

> > 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.

Things got even more interesting: I hooked yet another disk on the bus (A 
Quantum Viking II), and now _all_ the disks attach with 10 MHz. Does the 
host adapter actively probe the SCSI bus for bandwidth and signal quality? 
I assume the 2940 does not have a wide-narrow bridge circuit: How do the 
narrow devices influence autoconfiguration of the bus? Removing the narrow 
cable made no difference.

         hauke



--
Hauke Fath                              Saphir Software GmbH
                                         D-69115 Heidelberg
hf@SaphirSC.DE                          Ruf +49-6221-13866-35, Fax -21