At 05:33 AM 3/18/00 +0000, Eric Smith wrote:
>Clustering?  Is DSSI a multi-master bus?

Yup.

>Can I just plug two vaxes onto the same DSSI disk drive?

Yes again. Make sure your two hosts have different IDs.

>   I assume I'd need to configure one
>of the DSSI controllers specially?  (This can be done with SCSI as long
>as both controllers are set to unique IDs, and termination is done
>right.)

Nothing particularly special. Its one of the reasons why DSSI chains _must_ 
be terminated. Since controllers always are terminated it works.

>Even if this is physically/electrically/logically possible, I'm reasonably
>certain that the NetBSD filesystem code isn't going to support two hosts
>mounting the same filesystem, unless both mount it read-only.

Well at least one of them should mount it read only :-)

Actually how it would work is probably determined by how you treat the DSSI 
bus, if you treat it like a network and have the "master" host export the 
disks with something like NFS then that might work (although it would be 
weird going over the bus to the master processor to have it get the data 
from the disk and then return it back over the bus ;-)

One of the more intriguing things will be to see if the SMP work will 
support cross calls.

--Chuck