19 Feb
2013
19 Feb
'13
12:03 p.m.
Jeff Jonas [jeffj at panix.com] wrote:
OpenVMS AXP and I64 support partial clustering over some SCSI adapters, but I wouldn't
call it full
"networking". The machines are configured as multiple initiators and can send
storage requests over
the SCSI bus to shared disks or arrays. You still have to have another connection (usually
Ethernet)
for machine->machine cluster communication.
While I haven't looked into it much beyond pinouts, DEC produced the proprietary DSSI
which, in some
cases, used SCSI ASICs - indicating that at some level it was similar (HSD-05 used, I
think, an Emulex at
either side. Can't check now, but can later). The protocol was different, and cluster
communications could
go over the DSSI bus between machines.
I'm not sure whether the lack of a similar setup for SCSI is more because of
impossibility or because Fast/Gig
Ethernet came about and there was no longer much of a reason to not use the Ethernet for
cluster comms.
Long ago when SCSI was young
and just an 8 bit parallel bus,
Ampro littleboards advocated using the SCSI bus
for peer to peer communications, not just master/slave.
Did anyone else do that?
I don't remember the details but I'm fairly sure you could run
OpenVMS clusters over SCSI at some point. I don't recall
whether this was "just experimental" or whether it was
actually supported in some configurations.
Antonio