Newbie Question About System Update

Bill Moran wmoran at
Fri Apr 22 07:09:12 PDT 2005

Matthias Buelow <mkb at> wrote:

> Bill Moran <wmoran at> writes:
> >Fact is, trying to update a running system could result in silent failures.
> >The system can not replace programs that are in use, so there's always the
> >chance that something or other won't get updated (cron would be an excellent
> >example ... do you always shut cron off when you update?  How about syslogd?)
> This is complete nonsense.

Yes, and no.

As was pointed out, the install process does not "cp", so it doesn't have
to deal with this problem.  I was wrong.  However, it's still true that
you can't copy over an executable in use, it's just easy to work around

> >On a production system, you should have a serial terminal connected so you
> >can go to single-user mode remotely to do updates.  There are fairly
> >inexpensive serial terminal boxes available from a number of vendors, and
> >if you have a spare machine available, you can always hook it up as a
> >serial terminal.
> I was talking about a colocation situation, where you most likely will
> never see the machine.  Networked console boards are usually available
> but may not always be cost effective.  I would agree that such a board
> may be a necessity in a high profile production server but if you are a
> small company, or use a machine privately, the extra cost often
> outweighs the gain.  And a good colo hoster usually also has qualified
> staff.

Who are you using for colo?  I'd like to contact them.

Unless your server is utterly unimportant, the last thing you want to
have happen is an upgrade where the kernel doesn't boot and you have a
dead system until someone can hook a console to it.

Most colos I've seen charge you a premium to have someone hook a console
up for you.  I asked one how much it would cost to hook up a serial console
and give it an IP for one month, and their response was "we don't do that,
you have to pay our tech $160/hour to sit on the phone with you and enter
what you want."  While this seems to be a worst case scenerio, it doesn't
seem to be an uncommon attitude.

A lesson to all of you, when you choose a colo, don't just look at the
cost of having your box sit there - estimate the cost of doing maintenance
and handling problems, those are hidden costs where many colos will rape

Bill Moran
Potential Technologies

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