From Viraj Mody of the Microsoft Live Mesh team sent this my way: Dan Farino About MySpace Architecture.  

MySpace, like Facebook, uses relational DBs extensively front-ended by a layer of Memcached servers. Less open source at MySpace but otherwise unsurprising – a nice scalable design with 3000 front end servers with well over 100 database servers (1m users per DB server).

Notes from Viraj:

·         ~3000 FEs running IIS 6

·         NET 2.0 and 3.5 on FE and BE machines

·         DB is SQL 2005 but hit scaling limits to so they built their own unmanaged memcache implementation on 64-bit machines; uses .NET for exposing communications with layer

·         DB partitioned to assign ~1million users per DB and Replicated

·         Media content (audio/video) hosted on DFS built using Linux served over http

·         Extensive use of PowerShell for server management

·         Started using ColdFusion, moved when scale became an issue

·         Profiling tools build using CLR profiler and technology from Microsoft Research

·         Looking to upgrade code to use LINQ

·         Spent a lot of time building diagnostic utilities

·         Pretty comfortable with the 3-tier FE + memcache + DB architecture

·         Dealing with caching issues – not a pure write thru/read thru cache. Currently reads populate the cache and write flush the cache entry and just write to the DB. Looking to update this, but it worked well since it was ‘injected’ into the architecture.

I collect high scale service architecture and scaling war stories.  These were previously posted here:

·         Scaling Amazon: http://glinden.blogspot.com/2006/02/early-amazon-splitting-website.html

·         Scaling Second Life: http://radar.oreilly.com/archives/2006/04/web_20_and_databases_part_1_se.html

·         Scaling Technorati: http://www.royans.net/arch/2007/10/25/scaling-technorati-100-million-blogs-indexed-everyday/

·         Scaling Flickr: http://radar.oreilly.com/archives/2006/04/database_war_stories_3_flickr.html

·         Scaling Craigslist: http://radar.oreilly.com/archives/2006/04/database_war_stories_5_craigsl.html

·         Scaling Findory: http://radar.oreilly.com/archives/2006/05/database_war_stories_8_findory_1.html

·         MySpace 2006: http://sessions.visitmix.com/upperlayer.asp?event=&session=&id=1423&year=All&search=megasite&sortChoice=&stype=

·         MySpace 2007: http://sessions.visitmix.com/upperlayer.asp?event=&session=&id=1521&year=All&search=scale&sortChoice=&stype=

·         Twitter, Flickr, Live Journal, Six Apart, Bloglines, Last.fm, SlideShare, and eBay: http://poorbuthappy.com/ease/archives/2007/04/29/3616/the-top-10-presentation-on-scaling-websites-twitter-flickr-bloglines-vox-and-more

·        Scaling LinkedIn: http://perspectives.mvdirona.com/2008/06/08/ScalingLinkedIn.aspx

Updated: Corrected formatting issue.