> My more fundamental conclusion was that the whole master-master dream is a > myth: > it doesn't solve anything. It doesn't scale at all. > > Does it offer higher throughput?
NO > Does it offer lower latencies? NO > Does it offer higher reliablity? NO > Does it offer higher availability? YES! With the multi-master database performance is no better unless you have a massive read:write ratio. For most users I would say that this ratio would be down around 1:1 (or for users who don't read their spambox this could be lower reads to writes) Remember that all writes have to be applied to both databases, so performance on a busy site is going to be limited by this. The reason I will shortly be switching to a multi-master setup is that last night I spent a few hours after midnight fixing a problem with my current setup (mysql files on a drbd store with heartbeat) - a simple loss of network connectivity due to a switch that needed powercycling caused both servers to reboot a number of times while fencing the data store, and drbd failing to come up due to the network missing on the second server, therefore the primary server was unable to get to the mysql data. Since multi-master mysql does not give any performance benefits over a single instance (except maybe supporting a higher number of concurrent connections), I will be using one server only at a time, and switching to the secondary in a fail situation. I'll be using ucarp instead of heartbeat as it's lighter and faster. In this configuration there are no UID order issues, unless your system continually fails. And a network failure to the secondary machine shouldn't cause the primary to fail, as it did for me. _______________________________________________ DBmail mailing list [email protected] https://mailman.fastxs.nl/mailman/listinfo/dbmail
