It doesn't really work that way, though. With the same number of players online, the same number of chunks (more or less) will always be loaded regardless of the world (unless the players are all in the same places sharing chunks). With no players in the rest of the chunks of all those worlds, the files will lie dormant on the disk until a player visits them, at which time the chunks they were previously in will be unloaded.I shied away from mystcraft because of issues i have had in the past; on my old bukkit server we would run multiple maps (surv, creative, towny, etc) and had problems with the server keeping up with so many people on diff. maps
i automatically assumed having a shit ton of worlds running, with people on each world, would strain the crap out of my resources..
unless you run a ramdisk, then it really sucks XDIt doesn't really work that way, though. With the same number of players online, the same number of chunks (more or less) will always be loaded regardless of the world (unless the players are all in the same places sharing chunks). With no players in the rest of the chunks of all those worlds, the files will lie dormant on the disk until a player visits them, at which time the chunks they were previously in will be unloaded.
For example, one of my servers has a world map which is currently at over 12gb in size, but performance is only affected by the number of players online at the same time (and thus the number of chunks and entities loaded) not by the size of the map on disk.