Facebook Facts

• Generating a Facebook Page: email from Bob English (4/2/2010)
• Server configuration as of 3/24/2009:
  • 15000 Web servers running PHP (business logic, presentation)
  • 2000 memcache servers handling 50M queries/sec. (they claim up to 200K requests/sec/box)
  • 4000 database servers handle a total of 1M requests/sec.
  • 64GB RAM on each memcache server.
  • 600 nodes in a Hadoop cluster for data analysis
• Memcache RPC latency:
  • Server takes 70us to turn around data
  • Total latency 200us within a rack, 400-500us across datacenter
• Page rendering time: 300-400ms of CPU time on the Web server
• Code base: 2-3 million lines of PHP code in the front end
• Database:
  • Total size, not including photos: 200TB
  • Database servers have enough memory to cache half of the total data
• Each database server:
  • 8 2.5in discs
  • 1000 requests/sec.
• Photo data:
  • About 1PB total, as of 3/24/2009.
  • Maximum size for individual photo: 64-128KB.
  • As of 8/2008, they were getting 24M photo uploads/day.

Questions

Here are additional things we would like to know about Facebook:

• Of the 1M requests/sec to the database servers, how many of those are updates?
• What is the average payload size of a get/set request to Memcached?
• Hit ratio?