Ultrix 1.2 MAXUSERS

[Casey Leedom]

In article <41605 at felix.UUCP> ff at cpsvax.cps.msu.edu (Bruce McMillin) writes:
> 
> I am running Ultrix 1.2 on a VAX 8600.  As we climb up to 33 or so users,
> I am getting a warning about "maximum number of users exceeded".  This is
> strange since I have MAXUSERS set to 128 ...

  I don't know the exact details of this fiasco, but DEC ships an
ancillary tape along with their Ultrix distribution that actually allows
you to have more than two users running at a time.  This tape, when
installed (via /etc/install_upgrade), leaves a little binary turd file
(/upgrade) laying around that specifies the maximum number of users that
are allowed to be logged on at any one time.

  This information is recorded in the first byte of /upgrade.  If zero,
your system will support more that 64 users.  If non-zero, say N, your
system won't let more than N users log on.  And, if /upgrade is missing,
then your system won't let more than 2 users log on.  The program
/etc/license will print out the number of users your system will support.

  /upgrade is about 1000 bytes long (sorry I don't remember the exact
number), so I'm guessing that the remaining bytes form a redundancy code
that would prevent you from simply changing the first byte of /upgrade
to whatever you want.  But you'd have to check that out for yourself.

  What I'm stumped on is how the kernel is informed of the maximum number
of users.  There's a new error, EUSERS, which is documented as meaning
``Too many users'' in <sys/errno.h>, so I'm guessing that it's the kernel
which is used keep track of the number of logins.  But that's just a
guess.  The only thing I do know is that I haven't been able to find any
program besides /etc/license which accesses /upgrade and all that license
does is print out the maximum number of logged in users allowed (and I had
to get that by adb'ing license).

  My feelings about the whole scheme are totally unprintable.  I don't see
where DEC gets the idea that this is customer support.  I really wish
they'd spend less time screwing up the operating system and more doing
real work.  After all, it's nearly two years since 4.3BSD came out and
the idiots still haven't incorporated the name server!!!!  I'm at least
partially pissed off because I used to like DEC a lot and these days I
find it increasingly difficult to say good things about them.  Their
equipment is overpriced and wimpy and they look more and more like Big
Blue every day.

Casey