753 not seen in Sun-3/280 (not as long, torturous)

[Phil Ritzenthaler]

| On one occasion, which was not reproducible, the controller did
| see the drive in "format" but any attempt to do anything (read the
| label or find the defect list) there was a error as follows:
| 	Block error 0/0/0 : disk sequencer error
| (that's the approximate, not exact, message) and the operation would
| abort.
| 
| What is especially curious is one of these boards *had* been working; CNLS
| folks borrowed it and didn't report any problems.  Also, the other was in
| a 3/280 *and working*.  The only change was to attach the second command
| cable connector to another drive.  Both drives then disappeared (xdc0 at
| ... ee80 reported, but no xd0 or xd1 reported) and when the initial
| configuration was restored the controller would *not* see the drive it had
| been connected to, and working with, for weeks!
| 
| The jumper settings on the xy753 are fairly straightforward, and both
| controllers were configured as the first xd controller in their systems
| (xd0c at ee80).  As mentioned, one of these had been working for some 9
| months and the only change was to attempt to add a second disk to the
| controller.
| 
| We were wearing grounding straps at all times, the machine room itself is
| temperature- and humidity-controlled, and the machine room floor is very
| well grounded.
| 
| Does anyone have any clues as to what would be going on here?  Suggestions
| as to things to test?  All machines are running SunOS 4.0.1, and have at
| least one xy controller already.  The machine which *ran* with the xy753
| had two 451s in it at the same time.

Boy, does this sound familiar!!!!!!!!!  We had the same problems with the
753.  We tried different controllers and different 9U/6U adapters.  We
finally pinned it down to the crazy adapters.  

Did you try taking off the metal covber plate of the xylogics (the one
with the handles), and then place the controller right on the VME bus
without the adapter??  When we did this, the controller worked OK.  This
is what clued us into the adapter.

Good luck . . .

Phil Ritzenthaler  The Advanced Computing Center for the Arts & Design (ACCAD)
Systems Manager    The Ohio State University
                   UUCP: ...!{pyramid,killer}!grumpy.cgrg.ohio-state.edu!phil
                   ARPA: phil at grumpy.cgrg.ohio-state.edu

"Research is the process by which a loose brick is found through pounding
 one's head against a wall."  --  Anonymous