2.9 Service-Level Agreement
A service-level agreement (SLA) is a negotiated contract or agreement between a vCloud service provider and the consumer that serves to document the services, service-level guarantees, responsibilities, and limits between the two parties.
General guidelines for vCloud service providers require that any service offering made available carry a comprehensive service level agreement guarantee that is equal to or exceeds three 9s (99.9%) for availability and reliability, and includes special considerations for overall service performance and customer support handling and responsiveness. An SLA can either be a negotiated or standard contract between a vCloud provider and subscriber that defines responsibilities and limitations associated with the services:
Availability
(uptime).
Backups (schedule, restore time, data retention).
Serviceability
(time to respond, time to resolution).
Performance
(application performance, network performance).
Compliance (regulatory compliance, logging, auditing, data retention, reporting).
Operations
(user account management, metering parameters, response time for requests).
Billing
(reporting details/frequency/history).
Service credits or penalties.
Although detailed guidance on how to calculate the level of availability and performance for all vCloud service elements is beyond the scope of this document, it is anticipated that service providers have an SLA framework in place that can be leveraged or augmented to support vCloud services.
SLA guarantees should extend to all facets of a provider’s vCloud hosting infrastructure and individual service domains (for example, compute, network, storage, Layer 4 – Layer 7 services, and management/control plane) that directly support vCloud services. Adherence to SLA requirements should also factor in the resiliency of the management framework, consisting of API and UI accessibility for service subscribers.