Could you be a bit more specific on what you mean?

A) At runtime the game is always synced to disk?
B) At runtime the game is in RAM, but then persisted to disk at certain key points?
C) Something else all together?

Kev

Normally, IIRC, a disk-based MUD is one where you use HD + RAM instead of just RAM, thereby implementing your own memory-management system; this is a good opportunity to also implement semi-continuous synch to disk, so both your A and B often go hand in hand.

MUD's often have hundreds of thousands (sometimes millions) of mud-objects; the OS isn't anywhere near as intelligent at managing this as the MUD could be, and paging performance can be improved considerably. The last time I tried this, I found the same was still true of java (1.2.x I think) - that if you know a lot about the lifecycle of your "objects" (which may or may not be implemented on a 1-1 mapping with java objects) you can do a lot better virtual mem mgmt than OS + JVM would do for you automatically. Then again, some OS's (e.g. linux) can be incredibly bad at virtual mem mgmt even today, so this is not saying much!

1. Go to kanga.nu
2. Subscribe to MUD-DEV mailing list
3. Post this question there
4. Await detailed feedback from lots of other MUD-developers. Although, if it's been asked before on the list, you should google for

"MUD-DEV" disk-based [etc]

although if someone on-list rmembers a thread on it, they'll probably provide links and possibly search-terms.

thanks!