VAX 785 won't fully boot

[Chris Torek]

In article <707 at ulowell.UUCP> page at ulowell.UUCP (Bob Page) writes:
>Our VAX 11/785 (Ultrix 1.2) crashed the other day, with the message:
>
>machine check 0: cp read timeout or error confirmation fault

A `cp read timeout' is an SBI fault (usually?).  Look at the value
printed for `sbifs' (the SBI Fault Signal register), and get a copy
of the `red book' (the Vax Hardware Handbook, not the Red Book of
Westmarch).

>...  Some files were corrupted & corrected by fsck, until
>it couldn't do any more.  An operator fan fsck by hand and fixed
>the bad/dup inodes, rebooted and things came back up fine & dandy.
>
>A while later (could have been days, we weren't spitting dates at
>the console every n minutes) another message:
>
>uba0: uba error sr=10(IVMR) fmer=71 fubar=772150	[ honest, fubar! --BP ]

FUBAR stands for Failed UniBus Address Register.  No doubt the
DEC engineer who ... `engineered?' ... that one is still chortling.
IVMR stands for InValid Map Register, which is either a bug in the
driver (probably not) or a hardware problem in the Unibus adapter
(probably).

>uqssp0 being reset					[ uqssp0 ? -- BP ]

Never heard of a uqssp.  Probably a typographic error in the kernel;
`uba0' makes more sense here.

>uda50a0: hard error, [numbers]

Uh oh.

>... followed by two more 'machine check 0: cp read timeout or error
>confirmation fault' messages....  Also note that 772150 is the
>address of the uda).

I sense a hardware problem in the adapter, similar to the one we
had recently.  It invariably escapes DEC diagnostics.

>[more troubles]
>
>Now it won't finish booting at all.

Most likely a scrobiculate root file system.  (That *is* a word,
even if I bent its meaning a bit.  Look it up!)

>DEC FS has been in and run every diagnostic, replaced boards, etc,
>all to no avail.  The hardware is clean, according to DEC.

Hah.

>One suggestion DEC made is that Ultrix can't handle our 24-line
>DMZ's DMA, and that's why it was hanging.

Probably not.  The DMZ does have a peculiar tendency to drop master
sync, confusing the adapter, and it is safest to keep DMZs away
from other DMA devices, at least until DEC comes out with revised
ROMs.  But the symptoms do not match.