As others have pointed out, this post is from 2005. In the past 6 years, the cost of scalability has dropped sharply, and shooting for three 9's should be the

As others have pointed out, this post is from 2005. In the past 6 years, the cost of scalability has dropped sharply, and shooting for three 9's should be the minimum for most sites. It doesn't cost thousands to go from 98% to 99% any more, and to 99.9% is still pretty cheap. Sure, five and six 9's does get expensive, and that will depend on your cost of downtime (ie: lost sales, etc.).