[comp.unix.ultrix] Boot block trashed

greg@duke.cs.unlv.edu (Greg Wohletz) (01/05/90)

We have three microvax  II's that we  use as fileservers.  Each has  3
wren V's and   an exabyte hooked  into  a  Sigma  scsi  controler  (it
emulates  a  uda  and  tms controler).   They    also  have a dec  uda
controller hooked to  an  rd52 and two rx50's  (yes  we've have  these
machines for  a while...) on  them.   We have been  running with  this
configuration under ultrix  2.0 without  many problems (well a few nfs
bugs, but nothing major).  Recently we got ultrix 3.1.  I installed it
on one of  our microvax's  and everything seemed  to be  going fine, I
could use the disks, and read from the exabyte.  However, when I tried
to dump the root filesystem  to the exabyte  I got a write error, then
some message like ``mscp resynching controller uq2'' at that point the
system locked up.  Now that wouldn't be so bad, but after I halted the
machine and tryed to  boot  it   I got  the wonderfull  message  ``HLT
instruction''.  The boot  block  had somehow been  trashed.   Stranger
still is  the fact that  the boot  device (the little   rd52)  is on a
differant controller than  the exabyte.  The first  time it happened I
figured that I  must have just   done something  previously which  had
trashed the boot block, but after re-installing the boot  block on the
drive I was able to trash it again in the same manner.

So, perhaps the code that does the ``resynching'' makes bad assumtions
about the number of  disk controllers in a  system or something.   I'm
not  sure,  I'll investigate  it further after I  get a boot block put
back onto the drive again (hopefully that is all that was trashed...)

If anyone has any insite I'd appreciate hearing from them.

					--Greg