In cloud services, whether it is infrastructure as a service (IaaS), platform as a service (PaaS), or software as a service (SaaS), service availability is often a significant customer concern because the customer is relying on the vendor to provide and manage the infrastructure and related components that are necessary to provide the services. To address this concern, vendors will often provide a Service Level Agreement (SLA) containing a commitment that the service will be available for a percentage of time (e.g., 99.9%) during a certain period (e.g., week, month, or quarter). This is often referred to as an uptime or availability commitment. When reviewing and negotiating an SLA with an uptime commitment, it is important to consider the following issues.
Given the different types of cloud services and how those services are used, there is no standard uptime commitment provided by vendors. Rather, uptime commitments can range from 99.999% to 97% or even lower. It is also not uncommon for vendors to provide different uptime commitments for different parts of the service. Ultimately, a vendor’s uptime commitment will depend on a variety of factors, including the type of service, how a customer will use the service, negotiating leverage, and vendor’s business model.