Stupid me, here I was thinking if you run MySQL in multi master mode it should not have issues with writes coming in to multiple locations. I’ve never heard of any issues(at the same time it’s been a while since I’ve heard anyone talk about running multi master MySQL themselves), but apparently there are some as this guy is indicating, he has a webinar about it on November 15th. It sounds interesting to me, though I’ll be on the road that day so won’t be able to listen in, hopefully he posts the data afterwards.
At my current organization we do have multi master MySQL though we have yet to run them active-active (with writes going to both) for more than a short period at a time (usually just during fail-over events – “oh my god MySQL is about to crash fail over!”). The load balancing is handled by our Netscalers and their MySQL-aware load balancing. Overall the load is low enough(avg under 10% CPU and avg 75 write IOPS/DB – all reads being served from RAM) that I don’t think it’d provide any performance benefit to us anyway.
From the MySQL performance blog post
This talk gives an overview and concrete examples of how writing across dual-masters can and will break your assumptions about ACID compliance, how you can work around it, and some alternative solutions that are on the market today that attempt to address this problem. Â This will be a great session for DBAs just getting into this problem space, are moving from hot-cold architectures to hot-warm or even hot-hot, and even for developers to get a sense of the difficultly of this problem.