> You see greater performance if you commit in batches rather than after > each > message, as this means fewer disk synchs... Similarly if the message size > is larger then you get greater Kb/s throughput.
If you replicate the messages in memory (to another machine or two) you do not have to force to disk upon commit - you can thus take the disk out of the critical path. Therefore you can get great throughput even with short transactions and short messages. With the totem protocol you can create, say, 3 copies of all messages with a few milliseconds latency and a throughput of 25,000 messages per second that's with 1423-byte messages.
