Summary: 4 hosts per D1000 - no terminator

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Date: Fri, 30 May 2003 09:10:05 -0400
To: sun managers <sunmanagers@sunmanagers.org>

        Well, unfortunately only I had one response, and it was a request to
clarify my environment. Sun wont budge on this, and strangely enough,
they wont provide a technical reason why. So my choices are, support
it myself or remove 1 hba from each scsi bus and terminate the D1000s.
I don't have any problem supporting it myself, but that leaves my
employer is a pretty bad position if I get hit by the proverbial bus.
So I've gone thee Sun supported route, I've terminated the D1000 and
mirrored the rootdg off into my san. This is kind of a waist of high
performance disk space, but at least the machine will be up if
something happens on my single scsi path...

Issue with my bus sharing configuration described in my original post
are:

1.) 1 bad hba may adversely affect a good hba on the same bus (two
domains or hosts affected by one hardware error).
2.) Maintenance requires more thought and planning because you may need
to break a scsi chain.
3.) Each domain must be booted one at a time because Solaris/OBP does a
SCSI reset during boot (this panics a booting domain, but not a fully
loaded and running kernel).

Since everything is mirrored, I haven't had a problem with any of these
issues. I used this configuration of over a year without any issues.
Obviously use at you own risk as Sun wont support you!

Regards,
-Eric

----
Eric P. Forgette
Unix Systems Administrator
http://homepage.mac.com/e4jet/sysadm/
Here is the original post:
Hello,
An urgent request as always.  I'm looking for the technical reason why 
Sun
wont support 4 hosts connected to 2 D1000 (each host having two paths to
each boot disk).  After reading "SCSI-Initiator ID" By David Deeths (Sun
BluePrints OnLine - August 2000), and having a pretty good understanding
of how SCSI busses work, it seems this should work great!  In fact, I've
been running 4 E10K domains duel pathed to 2 D1000s for over a year
without any issues (all scsi ports on the back of the D1000 have host 
buss
adapters hooked to them).  As long as you're careful to boot each box,
which shares a bus, one at a time (Solaris/OBP does a SCSI reset during
boot), it would seem that everything is cool.  I admit that debugging an
HBA issue would be more challenging, but one could just add a terminator
and test the suspect HBA.  Does anyone have any technical reasons why 
this
isn't supported?  Is anyone doing anything similar to this?
Regards,
-Eric
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