A "power"ful claim
Monday, March 15, 2010
11:09 AM
A "power"ful claim
The simple change of stating your availability in probabilistic rather than absolute terms can save surprising amounts of power. 
Rewriting the rules: 
Old SLA: 99.99% uptime. 
New SLA: 99.99% of requests get answered; other 0.01% doesn't get answered. 
These are very different requirements! 
The latter allows you to queue requests and defer them until systems are available. 
So general uptime can be much lower and still comply. 
So costs can be much lower. 