I wandered down to the full LiveJournal's Backend: A History of Scaling by Brad Fitzpatrick. Brad explained the history behind LiveJournal, the scaling from 1 server to hundreds of hits a second and the solutions built along the way. He's a good speaker and explains the history and little stories well, such as the pingpong between being CPU- and IO-bound, partitioning the data (leading to per-cluster sequences, careful user mover tool). A nice comparison of master-slave, master-master, MySQL Cluster and share storage (even using DRBD) solutions. There are lots of places to cache, but memcached is a very nice solution: "run instances wherever there's free memory". Web load balancing is a pain, which led to Perlbal, a fast, smart web server/proxy - the nice thing is making the load balancer intelligent to easily add features. Of course now you need a distributed filesystem for user pics etc., hence MogileFS, which I really like: simple and works (unlike, say, SANs). A good talk covering lots of open source software. Best quote: "Cold cache, sad".
