From: carl@SOL1.GPS.CALTECH.EDU (Carl J Lydick)
Newsgroups: comp.os.vms
Subject: Re: Mount verification timed out
Date: 30 Dec 1992 12:38:22 GMT
Organization: HST Wide Field/Planetary Camera
Distribution: world
Reply-To: carl@SOL1.GPS.CALTECH.EDU
NNTP-Posting-Host: sol1.gps.caltech.edu

In article <1992Dec29.105010.1@slacvx.slac.stanford.edu>, fairfield@slacvx.slac.stanford.edu writes:
=In article <1992Dec29.152302.1716@das.harvard.edu>, chen@speed.uucp (Lilei Chen) writes:
=> In our VAX/VMS-cluster a bunch of disks are cross mounted.  Somtimes when
=> a node goes down, its disks are marked mount verification timed out.  I
=> haven't found a way to get those disks remounted without rebooting the
=> nodes.  I am wondering if someone on the net has a solution for that problem.
=
=    For each node in the  cluster  for  which  the  disk(s) have gone into
=mount verification time-out, do:
=
=	$ DISMOUNT/ABORT device
=
=You can do this most easily from SYSMAN after doing
=
=	SYSMAN> SET ENVIRONMENT/NODE=(NODE1,NODE2,...,NODEN)
=
=where the node  list,  above,  includes  all/only  those  nodes needing to
=remount  the disk(s).  Follow the DISMOUNT with a MOUNT (with  appropriate
=parameters).  Note that it _is_ allowed to do a  second  MOUNT/CLUSTER  of
=the  device in question from it's local host (and perhaps from any node in
=the cluster, I haven't tried): all  nodes  for which the device is already
=mounted ignore the request, while nodes that don't have the device mounted
=will mount it.
=
=    As another followup pointed out, if there are any open channels to the
=disk(s) that "went away", they must  be  closed  before the disk(s) can be
=dismounted.   That's  why  you need to use /ABORT.  I am not sure  of  the
=current situation (VMS V5.5-1), but in earlier versions  of  VMS,  if  you
=issued  a  DISMOUNT to the device _without_ the /ABORT qualifier, the disk
=would  NOT  dismount  successfully,  even  if  you  subsequently  issued a
=DISM/ABORT (again, this is most likely dependent on having "open" files on
=the device in question from the node you're trying to do the dismount).  I
=recall  getting devices into a state of "Mount/Dismount"!  The only way of
=recovering those devices for _that_ node was to reboot. :-(

At last!  An intelligent and responsible answer to the question.  Several other
responses recommended actions that would've only made matters worse.

	PLEASE:  WHEN ANSWERING QUESTIONS IN THIS NEWSGROUP, DON'T GIVE ANSWERS
		UNLESS YOU'VE TESTED THEM!

I've held off on answering because, though I thought I knew the answer, I knew
that some actions would certainly make things worse (once you've got a disk in
the state "Mounted, marked for dismount" you can be in *REAL* trouble;  there's
no simple way to figure out who's got what open;  at best, you can use
ANALYZE/SYSTEM on each node in your cluster and check EVERY process's channel
listings to figure out who's got channels open).

FWIW, here's what the HELP utility (those of you who gave harmful answers HAVE
heard of HELP, haven't you?) has to say about DISMOUNT/ABORT:

$ HELP DISMOUNT/ABORT

DISMOUNT

  /ABORT

     Requires volume ownership or the user privilege VOLPRO (volume
     protection) to use this qualifier with a volume that is mounted
     neither group nor system.

     Specifies that the volume is to be dismounted, regardless of who
     mounted it. The primary purpose of the /ABORT qualifier is to
     terminate mount verification. The DISMOUNT/ABORT command also
     cancels any outstanding I/O requests. If the volume was mounted
     with the /SHARE qualifier, the /ABORT qualifier causes the volume
     to be dismounted for all of the users who mounted it.

The idiots who suggested using DISMOUNT without the /ABORT qualifier apparently
didn't know (or care) that DISMOUNT without that qualifier can put the disk
into a state where outstanding I/O requests *CANNOT* be canceled.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
Newsgroups: comp.os.vms