[MUD-Dev] Star Wars Galaxies: 1 character per server

Caliban Tiresias Darklock caliban at darklock.com
Sat Jan 11 12:23:45 New Zealand Daylight Time 2003

From: "Marc Fielding" <fielding at computer.org>
> [C.T. Darklock]

>>   1. Assume you can fit 50 characters on a server. (X)

>>   2. Assume each player can have 5 characters. (Y)

>>   3. Assume the average number of characters per player is 2.4
>>   (Z).

>>   4. You can fit a maximum of 50 players (X) and a minimum of 10
>>   players (X/Y) on one server.

>>   5. Since you have 500 players, you will need at least 10
>>   servers (F = P/X).

>>   6. Since each player can have 5 characters, you will need at
>>   most 50 servers (M = (P / X) * Y).

>>   7. Since each player already has 2.4 characters, you will need
>>   at least 24 servers (O = (P / X) * Z).

>>   8. Since you can't very well throw out existing characters, you
>>   have to provide servers for them (S>= O).

> This analysis has the additional complexity that a player has a
> limited number of characters to scatter across multiple shards.

Well, not really. It has the additional SIMPLIFICATION that all
players play on one and only one server, and that we will magically
accomplish putting each player's characters onto the same server
without having to pay much attention to it.

> The (more straightforward) version of MCS that I'm more familiar
> with allows up to X characters per server per player.

This is easily resolved by separating the concepts of customers,
accounts, and players, saying that each customer C has a number of
accounts A which includes a number of *presences* P, each of which
is a group of characters on a single server belonging to a single
account. We can then observe that C <= A <= P and pretend nothing
ever happened. All the math related to P still holds true, but now
you can relax, secure in the knowledge that an MCS network still
gets slaughtered by an otherwise equivalent SCS network.

We will continue to assume that we somehow magically get all the
characters for a given presence onto the same server when we need to
do so, because I don't want to bother with that question. It's not
really important, anyway.

>> Even if *everything* you develop will *theoretically* handle an
>> infinite number of characters, it will never be able to do so in
>> practice. There is simply no way around this problem.

> Sure there is.

How exactly do you propose that you can have an infinite number of
characters on a server in practice?

> The maximum theoretical capacity of a shard should be well above
> its functional capacity.

That's why M and O are different variables. If you choose to use
some kind of probability metric to determine what actually *belongs*
in the calculation of O, fine -- but there's no reason an SCS server
can't do the same thing, so it doesn't matter.

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