How do I calculate service availability to business user?
Our service should be available to 24x7x365 days, but there are so many dependent components (network, servers, links, application, Data center etc) supported by multiple vendors should be available to meet the requirement. Vendors are signed resolution SLAs for their supported components but don't have monthly availability metrics for those components. How can I calculate theoretically what would be the overall SLA for the service? I hope I am clear on my question, if not please do let me know.