Help with mvaxII/Ultrix crashing irreversibly

[Dan Ts'o]

In article <2355 at maccs.McMaster.CA> art at maccs.UUCP (Art Mulder) writes:
)	I am running a MvaxII, running Ultrix 1.2
)
)	It has been doing a good impression of a yo-yo for the past several
)months.  In fact since January, it has yet to be up for any 7-day period.
)These are not minor crashes either.  These are "boot sector of disk munched"
)crashes.  I think I've reinstalled ultrix on this baby more times in the
)past 3 months than anyone should have to.
)
)Hardware service has not been much help.
)	CPU board has been replaced
)	4mb Ram board has been replaced
)	Tk50 drive and controller have been replaced
)	disk drive and controller have been replaced
)	Mux has been replaced
)	Power supply has been tested - fine.
)The only thing that has not been replaced is a DiLog CQ1610 16-port mux.
)
)This is the error messages that we had today when it crashed most recently:
)  :
)  kda500: hard error, ra0a: hard error sn5886    (<- whole bunch of these)
)  :
)  start=0, len=120, fs=/usr
)  panic: allocg: map corrupted
)  Syncing disks...

	You didn't say what type of disk you are using.

	Ultrix 1.2, at least at our site, was a fairly solid release, as long
as you do fairly standard stuff. How do you use your system ? Anything
not straight forward ?

	We had a similar situation with a MVAXII, though our crashes were
usually not as diasterous as yours. After several CPU and memory swaps, the
problem went away. Who does your servicine ? Can you be 100% sure that the
"new" boards swapped in are perfect ?

	How was the power supply checked ? Just using a multimeter is not
enough. You should get a power supply monitor and run it 24-hours/day. Often
power supply problems are difficult to find but quite common. Are you anywhere
near the power supply capacity of your box (BA23 ? I think 25A or 35A +5).
Did you try changing boxes or backplanes ? Maybe you have a flakely backplane...

	Does every crash result in a "Boot sector of disk munched" ? You should
keep a spare bootable partition or floppy. Is every crash identical ?

	If you provide more information, I might be able to help...

				Cheers,
				Dan Ts'o		212-570-7671
				Dept. Neurobiology	dan at rna.rockefeller.edu
				Rockefeller Univ.	...cmcl2!rna!dan
				1230 York Ave.		rna!dan at nyu.edu
				NY, NY 10021		tso at rockefeller.arpa
							tso at rockvax.bitnet