Very interesting talk on the scaling challenge at WordPress.com given by Barry Abrahamson, CTO of WordPress.
Some key points:
- 500 million database tables
- 3 data centers in USA
- 400.000 shards moved per day
- storage on SSD
- ~10% of total infrastructure costs are related to backups
- ~500 GB / shard
- 50 million sites
- 2.200 servers, and 500 database servers
Compare this with infrastructure costs for WordPress.