[MUD-Dev] Distributed State Systems

[Thomas Tomiczek]

Alex Arnon wrote:

> So are we looking at a cluster with N+1 (or N+M) redundancy here?
> Tough problem for some domains, though possibly not for
> MUDs. Would a system which checkpoints the world state
> periodically, but which has no redundancy whatsoever, be
> considered viable for a large scale MUD/MMO? If so, what is the
> frequency of checkpointing you would desire? Or in other words,
> how much game time (not downtime) would players be willing to lose
> due to server failure before they start leaving: 1 minute, 5, 10,
> 30 minutes?

> If such a solution is acceptable, it solves some technological
> problems - you could tune your architecture for performance, with
> the addition of checkpointing logic (i.e., occasionally the DB
> server would message the cluster nodes to start sending in their
> changes to objects).

Why this approach?

Why not use a standard approach, as defined by databases, and write
changes to a log constantly, and on a restart, consolidate them into
the database.

The issue of having comples heavy operations performed in 100%
uptime with a guarantee of no changes being lost is not exactly a
new concept.  It has been solved for ages now in "serious
computing".

Thomas Tomiczek
THONA Software & Consulting Ltd.
(Microsoft MVP C#/.NET)
(CTO PowerNodes Ltd.)
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