Cloud Service Level Agreement (SLA)

SLA is a formal and legal contract document containing a set of well-negotiated objectives, purpose, terms and conditions of business engagements between the cloud service providers and the cloud users which has been mutually agreed to.

SLA also contains details of the cloud services to be rendered, benefits and drawbacks of the cloud, responsibilities, cloud deployment and security challenges as well as guarantees and warranties of the services.

This makes the pros and cons of the cloud adoption realities more transparent to prospective cloud consumers and serves as a common ground for interactions between cloud consumers and cloud service providers with both participating parties having a clear understanding of their pre-defined responsibilities, the mutually-agreed terms and conditions.

These agreements might include but not limited to what cloud services will be offered, the mode of service delivery and who will be responsible for the execution, monitoring, reporting failures, security, and privacy responsibilities.

Components of a Cloud SLA

A typical cloud service level agreement is composed of a service guarantee, service guarantee time and period, service guarantee granularity, service guarantee exclusion, service credit, and service violation measurement and reporting:

Service guarantee

This establishes the metrics which a cloud provider seeks to achieve within a service guarantee time period. Such metrics include cloud service performance quality evaluation parameters like disaster recovery, response time, availability and fault resolution time, and so on.

When these metrics are quantified and associated with a value, then a service guarantee emerges. Examples of a service guarantee includes response time (<40 ms), fault resolution time (within 30 minutes of detection) , availability (98.7%), and so on, and a decline by the service provider from meeting up with the service guarantee will add up as a service credit to the cloud consumer.

Service guarantee time period

This is the acceptable period of time required for a service guarantee to be met. It could be on monthly , daily or hourly basis and as well cloud be based on some other arrangements like the time span since the last system update was made, and so on.

Service guarantee granularity

This typifies the resources scale on which a provider defines a service guarantee. This granularity can be on per instance, per data center, per service, on per transaction basis or a service guarantee granularity can also be calculated as a collection of the concerned resources like transactions or instances.

Service guarantee exclusions

These are the possibilities and likely events that are not included in the service guarantee metric calculations. These exclusions might typically include instances like downtime due to a scheduled maintenance or abuse of the service by the cloud service consumer.

Service credit

This the accrued amount in favor of the cloud consumer or brought forward towards future payments for new services if a service guarantee is violated by a cloud service provider.

Service violation measurement and reporting

This identifies true violations of a service guarantee by defining how and who is responsible for measuring, and reporting of such violation(s), respectively.

Types of SLAs

Service level agreements can be multilevel, customer level, or service level based on the customer or the service.

Customer-based SLA

This is an agreement with the entity personal group which covers all services used by the users.

Service-based SLA

This is an agreement between the cloud service provider and all registered users using the service.

Multilevel SLA

This kind of SLA consists of different levels with each containing the conditions of different customers using the same service.

Customer level SLA

This document contains records of all service level management problems related to a group of certain users.

Service level SLA

This document contains records of all service level management problems related to a specific service for some group of users.

Importance of SLAs

  • It provides concise and transparent understanding of the cloud services and the cloud service providers.
  • It presents a list of all available services a service provider could provide with an associated detailed specification and description of each service.
  • It provides detailed information regarding business requirements and objectives in a transparent manner, including the respective expected responsibilities of the cloud consumers and the cloud service providers.
  • It showcases critical privacy and security management policies for the cloud environment.
  • It offers service-oriented monitoring of performance, service quality, responsibilities, and priorities.
  • It presents the service management requirements in a transparent manner if an event of a cloud service failure occurs.