hamm@BIOVAX.RUTGERS.EDU (01/18/88)
Here's one of those UFO's again. I apologize for the length.
I'm setting up a volume set for the first time on my VMS system, and
was doing some experiments last night to see how it worked before I
"go public" with it. Having initialized the disks (two RA-81s) and
done the initial MOUNT/BIND, I then was trying to make sure I understood
how to mount and dismount the packs properly, i.e., whether it made a
difference what order I mounted them, whether or not to use a single
MOUNT command, etc.
In doing this, I got into a state I've never seen before or since, and
can't reproduce. I'm hoping someone else can explain what silly error I
made, so I can be sure it won't happen again. The state was this: I
mounted the volumes, one after the other, like this, as nearly as I
can remember:
$ MOUNT DUB1: "Users.1" $users
$ MOUNT DUB2: "Users.2"
I did some tests to see what happened if I created files on $users, and
was dismayed to see them all appear on DUB1:. I then did SHOW DEVICE/FULL
on the packs, and now comes the strange part. Normally, I'd see this
at the bottom of the SHOW output for each pack:
Volume status: subject to mount verification, write-through caching enabled.
Members of this volume set are DUB1: (rvn 1), DUB2: (rvn 2).
But *this* time, I got the following for DUB1:
Volume status: subject to mount verification, write-through caching enabled.
Members of this volume set are DUB1: (rvn 1).
and this for DUB2:
Volume status: subject to mount verification, write-through caching enabled.
Members of this volume set are DUB2: (rvn 1).
I'm not *absolutely* certain that the rvn was 1 for DUB2:, but I think it was,
because I remember being surprised that the "relative volume number" displayed
above this in the SHOW output was correct for each pack, i.e., 1 for DUB1: and
2 for DUB2:. F$GETDVI also showed the correct rvn for each pack.
At this point, it was late, and I thought I'd best get some sleep and have
another look this morning (and probably re-init the packs, etc.) This
morning I came in, did
$ mount DUB1:,DUB2: "Users.1","Users.2" $users
and everything worked perfectly. I thought perhaps I mounted them last night
in the wrong order, so I dismounted them again, and tried:
$ mount DUB2: "Users.2"
$ mount DUB1: "Users.1" $users
Everything fine again.
The only other possibly relevant detail I can remember is that the
first time I tried mounting them as a volume set, I screwed up one of the
volume id's, so that an operator request was generated to mount the correct
volume. But then I canceled that, the operator request was cancelled, and
I went on from there.
At this point, everything works, but I have an insecure feeling. Can anyone
explain this behavior?
Thanks,
Greg
------------------------------------------------------------------------------
Gregory H. Hamm || Phone: (201)932-4864
Director, Molecular Biology Computing Lab ||
Waksman Institute/CABM || BITNET: hamm@biovax
P.O. Box 759, Rutgers University || ARPA: hamm@biovax.rutgers.edu
Piscataway, NJ 08854 * USA ||
------------------------------------------------------------------------------
------