Each item can be replicated to many machines, but written by one machine at a time. Galaxy works best when items that are replicated to many nodes are updated infrequently. This works very well when distributing data structures like B-trees, when the root of the tree is read by all but updated rarely, while the leaves remain pretty much confined to only one node and are updated regularly.
This is all for latency reasons. Fault-tolerance is a different story.
Ok. Makes perfect sense for B-Trees (as long as you have enough remaining memory/machine for a decent size cache). I think for a game's partitioned scene graph, the change rate would be rather painful.
This is all for latency reasons. Fault-tolerance is a different story.