The problem with these systems is they don't know what is significant state so they have to copy everything to the slave.
The way Remus gets round this is it bulk copies (upto 40 times a second) rather than on every change. So the master runs slightly ahead.
Terracotta is something similar for the JVM. I think they get round it by exploiting the fact the JVM knows what's going on so for example you could say I want only this field on a class to be replicated. (But I've never used terracotta so someone might have to correct me on that.)
The way Remus gets round this is it bulk copies (upto 40 times a second) rather than on every change. So the master runs slightly ahead.
Terracotta is something similar for the JVM. I think they get round it by exploiting the fact the JVM knows what's going on so for example you could say I want only this field on a class to be replicated. (But I've never used terracotta so someone might have to correct me on that.)