Читать книгу The Official (ISC)2 CCSP CBK Reference - Leslie Fife, Aaron Kraus - Страница 53

Availability has two components. The first is one leg of the CIA triad. Within the constraints of the agreed-upon SLA, the purchased services and company or individual data must be made available to the customer by the CSP. If the SLA is not met, the contract will spell out the penalties or recourses available. In this example, if a customer has paid for Dropbox, but when they try to access the service, it is not available, the service availability fails. If this failure is not within the requirements of the SLA, the customer has a claim against the service provider.

The second component of availability is concerned with the elasticity and scalability of the cloud service. If the CSP has not properly planned for expansion, a customer may need to grow their use of the contracted service, and the resources may not be available. Consider a service like Dropbox. If the customer pays for 2TB of storage and it is not available, when they need it, the service fails in terms of availability, even if access to files already stored with the service continues to be provided.