multi scsi questions

[Karl-Heinz Herrmann]

On 07-Jul-99 Danny Park wrote:
> suppose you have a scsi card (2940U for example) whose bios only
> recognizes scsi id's 0-7.  and say you have another card (2940UW) that
recognizes 0-15. naturally you'd make put the first controller at id 7 and
the second at id 15.

Sorry, I don't get the complete picture. 

1) Do you want to put the two controllers on *one* SCSI-Bus?
2) Or do you wan't to use both cards, having two separate SCSI-Buses with
   their respective own devices?

In Case 1) I don't think this is working just like that yet (And why do you
want it anyway?)
In Case 2) there would be two completely separate SCSI Buses and the ID's
of the one have nothing to do with the other.
It's like scsi-controller 1, id 0-7 AND scsi2, ID 0-15.
In Linux you will see that as scsi0 and scsi1 for the respective controller.
The devices (e.g. harddrives) will be labeled first all from scsi0 then all
from scsi1 (sda, sdb, sdc,..../ sg1,sg2,sg3,...  )

> 
> the question then is this:  does the first card "own" the 0-7 id space? 
> that is, will it cause problems if i, say, put a hd at id 1 on the
> second controller?
 
> another question: given that the hardware (the disk itself) only has
> three jumpers to set the id, how does one add 8 to the id to get it
> into that upper id range?  or will that only work for devices that
> support it?
Only Widecontroller have ID's above 7, and only wide devices can use ID's
above 7. You can't use a non-wide device on ID's like 11. 

And it seems[1], that non-wide devices "see" a call to a wide device with 
ID 9 on the same SCSI-Bus as a call to ID 2 -- If there is a non-wide
device with ID 2 it will/can get confused.

So in your case put all narrow devices on the U adapter and the wide
devices on the UW adapter and you should be fine. To get both adapters
running at the same time try locating the aicxxx Dokumentation and README
files in the kernel-tree or on the WWW. You probably will have to tell the
kernel that there are two adapters.

K.-H.



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E-Mail: Karl-Heinz Herrmann <k.-h.herrmann at fz-juelich.de>
Date: 07-Jul-99      Time: 18:17:20
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