SUMMARY: SCSI controller numbers differ on two identical servers?

Thanks to Darren Dunham, Ryan Bishop, Scott Mickey and Paul Richards for
assistance with this problem.

Paul Richards in particular in one terse message provided the explanation
for where Solaris keeps its cN -> device mappings -- in /dev/cfg.

So the answers I have determined to my questions are:

1) Q: Why did system A configure the second differential card as c4 when

      there were not five SCSI controllers in the system?
   A: There were four SCSI controllers, true, but also four FC-AL
      controllers built in to the two SBUS IO cards.  Even though these
      did not have the fiber modules installed, they still were counted.
2) Q: Why did the two machines configure differently?
   A: Not really understood.  For some reason system A saw two of the FC-AL
      interfaces before the second Differential card, and system B did not.
3) Q: How does Solaris decide what cN number to assign to a controller?
   A: Taking the next unused one in /dev/cfg, that contains a named link for
      every configured controller in the system, e.g. on my system:

db2# ls -l
total 16
lrwxrwxrwx   1 root     root          46 Dec 18 22:20 c0 ->
../../devices/sbus@3,0/SUNW,fas@3,8800000:scsi
lrwxrwxrwx   1 root     root          44 Dec 18 22:20 c1 ->
../../devices/sbus@3,0/QLGC,isp@0,10000:scsi
lrwxrwxrwx   1 root     root          51 Dec 18 22:20 c2 ->
../../devices/sbus@2,0/SUNW,socal@d,10000/sf@0,0:fc
lrwxrwxrwx   1 root     root          51 Dec 18 22:20 c3 ->
../../devices/sbus@2,0/SUNW,socal@d,10000/sf@1,0:fc
lrwxrwxrwx   1 root     root          44 Dec 18 22:20 c4 ->
../../devices/sbus@6,0/QLGC,isp@1,10000:scsi
lrwxrwxrwx   1 root     root          51 Dec 18 22:20 c5 ->
../../devices/sbus@6,0/SUNW,socal@d,10000/sf@0,0:fc
lrwxrwxrwx   1 root     root          51 Dec 18 22:20 c6 ->
../../devices/sbus@6,0/SUNW,socal@d,10000/sf@1,0:fc
lrwxrwxrwx   1 root     root          46 Dec 18 22:20 c7 ->
../../devices/sbus@7,0/SUNW,fas@3,8800000:scsi

4) Q: Is there anything I can do to make the two systems match?
   A: What I did was to give system B the same /etc/path_to_inst, /dev/cfg,
      and /dev/[r]dsk/c?t?d?s? entries.  Since the two systems have the 
      exact same hardware configuration, this should work, and it indeed 
      does seem to, even surviving reconfiguration boots.

Thanks, everyone, for your help.

-Matt

-----Original Message-----
From: Matthew Brown 
Sent: Thursday, December 19, 2002 1:01 PM
To: 'sunmanagers@sunmanagers.org'
Subject: SCSI controller numbers differ on two identical servers?

I have two I believe identical e4500 systems that I want to configure to
share two D1000 arrays in a failover kind of configuration - where they're
both connected at either end of the SCSI bus, but only one system mounts the
disks at any one time.  I'm wanting to use DiskSuite's disksets feature to
manage the disks.

I installed one of the systems and configured it up, and it decided that the
two Differential cards in the system were c1 and c4, for whatever reason.
The second system wants to see them as c1 and c2.  I cannot get the systems
to agree.

According to the SDS documentation, both systems have to see the disks as
the same controller, unit etc. in order for the disksets failover to work.

Both systems have the cards in the same SBUS slots.  There are two SBUS IO
boards in each system.  On the first, the controller is in slot 0, the
second has the controller in slot 1.

I have even copied the /etc/paths_to_inst file from the first system to the
second and boot -r to see if this will make the systems agree, and it does
not.

So my questions are:

1) Why did the first e4500 configure the second Diff card as c4 when there
are not five SCSI cards in the system?  
2) Why did the two systems decide on different configurations when, to the
best of my knowledge, they are the same hardware configuration?
3) How does Solaris decide which c? number to assign to a controller?
4) Is there anything I can change to make the second system think Diff card
#2 is c4, or anything I can change to make the first system think the card
is c2?

Thanks in advance for any help.

-Matt
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