[DGD] DGD/MP & OpenMosix revisited?

[Ragnar Lonn]

On Sun, 8 Feb 2004, Greg Lewis wrote:

> I would assume from the subject including "OpenMosix" and the body of
> the message mentioning "clusters" a couple of time that Ragnar was
> thinking of the servers all being in one or more racks connected with
> high speed interconnects (at least GigE, or possibly Myrinet, Quadrics
> or the like).

Yeah, I was thinking about GE myself. It is very cheap and available.

> The bottlenecking object type question would really come down to a
> question of designing the mud for a clustered environment.  Basically,
> don't design the mudlib around an object that will create such a
> bottleneck.  This is quite similar in some respects to design of a
> parallelisable program - you have to design it as such and shift your
> paradigm from what you use when designing a program that will be executed
> in a "serial" environment.

That's exactly what I think too. I'd like to hide the fact that the system
is built from a large number of separate machines from the average
programmer as much as possible but I don't think it can be wholly
transparent. Mudlib programmers need to know the physical layout of
the system very well. *They* might be able to hide a lot of it so that
simpler programmers won't have to think so much about it though, and
that's important.

Some games divide their world according to geographical location and
let a server keep track of a certain area. This might work but it
gets hard to optimise - likely you won't get an evenly distributed
load between your servers and things in the game might change that
affect the load pattern, something which you're then not so well
prepared for. It is not unusual today with games that have no failover
either. If a server is down, that area is inaccessible. This is a
practise that would not be tolerated for any other kind of Internet
service and I don't think games should do it either.

I'm curious as to what problems people on the list see with these
ideas. Synchronization problems, for instance?  What are the major
obstacles in implementing this?

  /Ragnar

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