9 Dec
2013
9 Dec
'13
9:48 a.m.
On Mon, Dec 09, 2013 at 10:51:38AM -0500, Paul Koning wrote:
On Dec 8, 2013, at 9:22 PM, Charles Dickman <chd at
chdickman.com> wrote:
> [...] The MSCP
> disk unit numbers are unique across all controllers and need to be set on
> each controller.
That depends on the OS. What you say is true for RSTS,
which refers to all
MSCP disks as "DU" and wants the unit number to be unique among all the
controllers. VMS refers to disks by type, controller, and unit, e.g., DUA2:
so (I would assume) it can handle duplicate unit numbers as DUA2: and DUB2:.
I'm 99% sure the "units are unique on a system" rule is from the MSCP spec,
so it certainly makes sense that RSTS follows it. It seems like kind of a
silly rule though since it's not true of anything but (T)MSCP, so any OS will
already have to have a plan for dealing with dupes (or officially refusing
to -- like the way RSTS rejects duplicate slave #s on Massbus tapes).
John Wilson
D Bit