We currently have 33 physical servers at Rackspace:
GitHub: How many physical/virtual servers does GitHub have? - Quora
- 2 database (mysql, redis)
- 6 frontend (rails, resque)
- 18 file server (9 pairs: masters serve git data, slaves run memcache)
- search
- xen (load balancer, ci, pages, service hooks, etc)
- staging
意外とコンパクト。