(i) a document that calls itself an SLA can define the denominator of the uptime fraction in any way it likes. By the time a vendor has excluded scheduled maintenance, or unscheduled maintenance with more than X hours’ advance notice (for example), an arbitrary number of 9s can be achieved without actually giving the customer what’s needed in terms of actual availability.

(ii) actual availability, quantifiably displayed via public dashboards and with full disclosure of every service anomaly, is what should actually be compared among both cloud and on-premise alternatives. If that means I’m saying that “saleforce.com’s numbers…speak for themselves,” I guess I’m also saying that nothing else can speak for them. Everything else, it seems to me, is just hopes and artful representations.

Thanks for putting these key issues on the table: I agree, or at least I believe we agree, that at this point it’s more important for cloud providers to join in combat against ignorance and FUD than it is for cloud providers to seek advantage over each other. Achieving understanding of the cloud is Job One for all of us.

– pc