[comp.os.vms] System problems after deleting dump file

LEICHTER@VENUS.YCC.YALE.EDU ("Jerry Leichter ", LEICHTER-JERRY@CS.YALE.EDU) (12/28/87)

	We recently deleted our sysdump.sys file.  Strange things have been
	happening ever since then.  I don't know if it is a hardware problem
	or what, but here goes:

	When we bring down the system, we find that when we come back up, that
	about 50 files have been stepped on.  These almost always occur in
	certain user's accounts (No, I KNOW that it isn't these user's doing
	it.  It IS something else.)  I wonder if it has anything to do with
	the Dump file.  We have a Double Eagle (Fuji) with an Emulex QD33 (or
	maybe 32) controller.  Is this a hardware problem, or something that
	is connected to my blowing the sysdump.dmp (or what ever it is called,
	the exact name escapes me right now...)???

Did you just outright DELETE the dump file on a running system?  If so, that
was the cause of your problems.  VMS accesses the dump file through a low-
level mechanism independent of the file system.  It will continue to access
the blocks that constituted the dumpfile at the time of the last boot, what-
ever you do to the file while the system is up.  If you delete the file,
its blocks will start getting allocated to other uses.  The next time the
system goes down - even if it's brought down deliberately - VMS will write a
dump over the blocks it THINKS are still in the dump file, clobbering whatever
is now there.  The result can be anything from no effect at all, if the blocks
aren't in use; to clobbered blocks within files; to trashed directories (if
the blocks happened to get used for directories); to who knows what.  It seems
that your disk has gotten damaged in a pernicious way.

The first thing to try is an ANALYZE/DISK.  See what kinds of errors are
reported.  Eventually you'll want to try an ANALYZE/DISK/REPAIR, though given
the problems you have, I'd recommend doing a full backup first!  In fact, it
might be simpler to do an image backup and restore and forget about trying
to /REPAIR the disk.  It's still worth doing the ANALYZE; if it reports
nothing significant wrong, then I'd look elsewhere (at the hardware).

The ONLY safe way to get rid of any of the VMS system files (pagefile, swap-
file, or dumpfile) is to rename the current file to some name that VMS will
not use the next time around, then re-boot.
							-- Jerry