Lisp stopped itself...

[gadbois@cs.utexas.edu (David Gadbois)]

    Date: Sat, 14 Sep 91 22:05 PDT
    From: Scott_Busse%mindlink.bc.ca@Warbucks.AI.SRI.COM (Scott Busse)

    (help!)
    The situation:
    On about the fifth time I have booted this machine (a 3650 with FPA,
    736 Meg CDC drive, running Genera 7.1), I have come up against an error which
    will not allow Lisp to run.

    [...]

      Lisp stopped itself.
      Halt reason ("Disk Error ~D, operation ~D, ~
      <211><211><211> Unit ~D, cylinder ~D, head ~D, sector ~D,
	     continue to retry." " %DISK-ERROR-SEARCH 11(8) 0(8) 2402(8) 21(8))

    [...]

My initial idea was that you had a bad disk block.  However, the disk
address you gave was on unit 9 (#o11), which seems unlikely.  Perhaps
something else is wrong, or maybe you just mistyped it.  If the former,
you are your own, but if its the latter, you can do

    (si:fix-fep-file
      (car
	(si:get-file-containing
	  (si:dpn-from-address #o11 #o0 #o2402 #o21))))

substituting in the right disk address.  Since this is a repeatable
error, there probably really is a bad block in one of your paging files
or world loads.  SI:FIX-FEP-FILE will scan the file and ask you if you
want to splice out the bad block.  The only tricky thing is that if the
bad block is in a critical place, you may have to use different
combinations of paging files or a different world load in order to get
Lisp running cleanly enough so that you can fix the problem.  And if the
problem is in a world load, you will have to get another copy of the
world after you nuke the bad block.

Note that if you start getting a lot of bad blocks your disk is probably
moribund, but it may last months or years before it goes completely.
However, I would be sure to make frequent backups and have an alternate
disk installed (with worlds, microcode, etc) before it goes to that
great disk farm in the sky.

--David Gadbois