[MUD-Dev] Virtual machine design

[Mik Clarke]

Eli Stevens (KiZurich) wrote:

> I was wondering what the general consensus on "not having to reboot" meant
> to the list.  Obviously, if the power goes off to the system the MUD is on,
> the MUD will have to reboot.  What must be supported on-the-fly for a MUD to
> be considered rebootless?

I work on an approach that considers the frequency with which you think the data
will need to be changed.  Rebooting every hour is not acceptable.  Rebooting
once a day is not good.  Rebooting once a week (assuming the mud can stay up
that long) is acceptable.  Rebooting never would be nice, but it needs more code
than a mud which is expected to be rebooted once a week.

Comercial systems (non-Mud) will generally have a 1 or 2 hour 'service slot'
during each week when their owners can changed things and reboot them (or even
reboot the server).  More critical servers (production line control, flight
control) will have much tighter windows, generally no more than a few hours on 2
or 3 days each year (and planned well in advance).  These are planned outages.
Some people spend a LOT of money to try to avoid and/or minimise unplanned
outages (due to hardware/software or site problems).  For a MUD, even a
comercial one, the benefit generally isn't worth the effort.

It is also important to split data into that which is dynamically updated and
that which is edited offline and picked up at reboot.  These two different types
of data absolutely must be placed into different files, so you can prepare
reboot changes offline and know that they won't be wiped out by someone doing
something online.

Mik




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