Cloud availability comes at a price

Unlike privately owned and colocated data centers, customers using the public cloud have no visibility or control over the data center used by their cloud provider. When architecting a cloud application, it is up to software developers to incorporate resiliency into their application architecture. Conversely, in a more traditional non-cloud application, data center teams, infrastructure engineers and software developers should work together to meet resiliency requirements.

Cloud providers offer a range of optional tools and services for developers to architect resilient applications, including geographically distributed locations (availability zones) and load-balancing services. Cloud providers' service level agreements (SLAs) and published reference designs offer some assurances of performance. However, these assurances are focused on their services, not their users' applications, and cloud SLAs provide minimal compensation in the event of an outage (see Cloud outage insurance: assessing policy options).