P1394 Mail Archive: Re: P1394> units and logical units definition

P1394 Mail Archive: Re: P1394> units and logical units definition

Re: P1394> units and logical units definition

Eric Anderson (ewa@apple.com)
16 Mar 98 11:07:42 -0800

Greg Shue writes:
> The SBP-2 proposal allows this to be modeled as:
> 1 unit with:
> 2 logins to the Print Job logical unit
> N logins to the Printer Status logical unit
> 1 login to the Printer control logical unit
> Similarly, since each of these services operate independently
> of each other (and may be used by other protocol stacks), SBP-2
> allows for them to be modeled as:
> 2 + N + 3 units with 1 logical unit each
> or:
> 1 Print Job Unit Directory with 2 logical units (instances)
> 1 Device Status Unit Directory with N logical units (instances)
> 1 Device Control Unit Directory with 1 exclusive logical unit
> The current PWG proposal restricts the options to the last one.

Even if each of those models is allowed by SBP-2, I think
the first one (a single unit with multiple LUNs) is both more
in the spirit of SBP-2 and more in the spirit of 1394. This
model allows a 1394 node to have any number of independent
printer units, which is good if you are a multi-function node
like a computer or a fancy printer.

The other model is difficult if you want to have multiple
independent units in a node, because there is no clear way
to match up which Device Status Unit Directory goes with which
Device Control Unit Directory, or Print Job Unit Directory.
Rev 0.1d of the profile doesn't show how to do this (or I
missed it...)

So at face value I would prefer the first model (above) over
the second.

Eric Anderson ewa@apple.com
Apple Computer, Inc. 408-974-8187