I'm working on a new map and I've noticed that when the server_level.dat file goes over 1 MB the map fails to load. I'll go to the external URL and the progress bar will begin loading, but around 3/4ths the way through it will just permanently stop. If I close the window and check my server window there's an out of memory error for Java. Is 1 MB really the max size for minecraft levels?
Neverless, a 512x512xerm, 384 turns out to be only 96 kb. Whether or not this changes when downloading it I do not know.
Ah, sorry I was thinking divisible by 2. I'm using custom heightmaps on my server so it has a lot more data in it that regular random generation servers. That's why my file is so large. 1MB seems kinda low for a level size limit.
I have successfully made and tested a 1024x1024x192 map. Comes in at about 877kb. I did notice, however, that at that size, the server seemed to be having trouble keeping up with changes made to the map in gameplay. When building, sometimes the things you build would momentarily disappear then reappear, and deleting things didn't always have an effect right away, especially when water was involved. It'd take 10-20 seconds for water to realize that hey, there's room to expand before doing it. When it finally did, however, everything seemed to progress at a normal speed.
I'm guessing that that probably has to do with however the server keeps track of the map to update it for everyone else. It seems to me like it's constantly checking every block to see if there was any change made, and when you have a map that big, it takes quite a bit of time to check before it gets back to whatever area you're editing at the time. It seems to me as though it'd be more efficient of the server to keep specific track of the areas directly around players to watch for changes, while crawling through the tiles that have automatic changes, such as water, lava, and grass. But I'm not a programmer, so I don't even know if that's feasible or not. Either way.
Big levels are awesome. It'd just be nice if they were a bit more playable. And if they could be over 1mb.