On Tue, 12 Feb 2008 13:28:15 -0600
James Bottomley [off-list ref] wrote:

On Tue, 2008-02-12 at 11:07 -0800, Kristen Carlson Accardi wrote:

quoted

I understand what you are trying to do - I guess I just doubt the
value you've added by doing this.  I think that there's going to be
so much customization that system vendors will want to add, that
they are going to wind up adding a custom library regardless, so
standardising those few things won't buy us anything.

It depends ... if you actually have a use for the customisations, yes.
If you just want the basics of who (what's in the enclousure), what
(activity) and where (locate) then I think it solves your problem
almost entirely.

So, entirely as a straw horse, tell me what else your enclosures
provide that I haven't listed in the four points.  The SES standards
too provide a huge range of things that no-one ever seems to
implement (temperature, power, fan speeds etc).

I think the users of enclosures fall int these categories

85% just want to know where their device actually is (i.e. that sdc is
in enclosure slot 5)
50% like watching the activity lights
30% want to be able to have a visual locate function
20% want a visual failure indication (the other 80% rely on some OS
notification instead)

When you add up the overlapping needs, you get about 90% of people
happy with the basics that the enclosure services provide.  Could
there be more ... sure; should there be more ... I don't think so ...
that's what value add the user libraries can provide.

James

I don't think I'm arguing whether or not your solution may work, what I
am arguing is really a more philosophical point.  Not "can we do it
this way", but "should we do it way".  I am of the opinion that
management belongs in userspace.  I also am of the opinion that if you
can successfully accomplish something in user space, you should.  I
also believe that even if you provide this basic interface, all system
vendors are going to provide libraries on top of that to customize it,
so you've not added much value to just a simple message passing
interface.

So, I'm happy to defer to Jeff's judgement call here - I just want to
do what's right for our customers and get an enclosure management
interface for SATA exposed, preferrably in time for the 2.6.26 merge
window.  If he prefers your design, I'll disagree, but commit to his
decision and try to get this to work for SATA. If he'd rather see
something along the lines of what I proposed, then since it is 100% self
contained in the SATA subsystem, it shouldn't impact whatever you
want to do in the SCSI subsystem.

Jeff?