I recently released the first, second and third installments of a six-part blog series about what it takes to have an enterprise-ready cloud service, and the three characteristics that differentiate an enterprise-grade cloud service from a typical consumer service: security, reliability and trust. As a quick refresher, there are five categories to look at when evaluating a cloud service for security, reliability and trustworthiness: Development for the enterprise Endless 9s reliability Benchmarked and audited service Strong encryption throughout Singular focus on the customer I’ll focus on “endless 9s” reliability in this post. Availability of a cloud service is important. People I know get quite agitated when Facebook or Twitter is unavailable, but imagine the repercussions when a big enterprise such as Genomic Health can’t access a critical application, such as CRM. The phrase “four 9s availability” has been the benchmark for providers delivering critical online or hosted cloud services.