Ever since I’ve started experimenting with HyperDB I thought that once I’ve got enough servers at my disposal, and if I ever figure out how to setup MySQL replication I’d bring the two together. I believe that day has finally come: HyperDB is now deployed across over 60 sites I’m taking care of.
I want to share with you my configuration and some of the pitfalls I’ve come across – if it helps, great. But mainly these notes are for me to remember how I did it when the next cluster needs to be built.