StackExchange's Performance Dashboard
StackExchange created a very cool performance dashboard that looks to be updated from real system metrics. Wouldn't it be fascinating if every site had a similar dashboard?
The dashboard contains information like there are 560 million page views per month, 260,000 sustained connections, 34 TB data transferred per month, 9 web servers with 48GB of RAM handling 185 req/s at 15% CPU usage. There are 4 SQL servers, 2 redis servers, 3 tag engine servers, 3 elasticsearch servers, and 2 HAProxy servers, along with stats on each.
There's also an excellent discussion thread on reddit that goes into more interesting details, with questions being answered by folks from StackExchange.
StackExchange is still doing innovative work and is very much an example worth learning from. They've always danced to their own tune and it's a catchy tune at that. More at StackOverflow Update: 560M Pageviews A Month, 25 Servers, And It's All About Performance.