Key Performance Indicators for Cloud Computing SLAs Stefan Frey, Claudia L¨ uthje, Christoph Reich Furtwangen University Cloud Research Lab Furtwangen, Germany {stefan.frey, claudia.luethje, christoph.reich}@hs-furtwangen.de Abstract—Reducing IT costs by using cloud computing is tempting for many companies. As cloud rapidly is gaining mo- mentum as alternative mean of providing IT ressources, the need for regulated service qualities increases. To attract companies to outsource their services to clouds, providers need to offer Service Level Objectives specified in SLAs for their customers. The content of such Service Level Objectives is a key reason for the successful usage of cloud computing and consists of Key Performance Indicators. Due to the dynamic character and complex nature of the cloud environment, creating SLAs for the cloud can be very difficult. This paper proposes selected KPIs for cloud SLAs and describes possible Service Level Objectives, as well as how they should be monitored. Keywords—Cloud Computing; KPI; SLA; QoS I. I NTRODUCTION After an initial hype, cloud computing has established itself as adequate means of providing resources on demand. By now cloud computing provides a practical alternative to, locally hosted resources for companies. The main benefits of cloud computing are the cost savings through its ”pay-per-use” model, low investment costs and its rapid implementation of innovations. According to a market analysis by the Gartner Group [1], the IT budgets of german companies has been reduced by 2.7% in 2011. The study also shows that companies will increasingly rely on outsourcing their IT to the cloud to save costs in the future. At present, most cloud computing providers only offer generic Service Level Agreements (SLA). Thereby guarantees for QoS characteristics like, bandwidth, data backup, etc. are given on the best-effort principal. Compa- nies require QoS, monitoring and control of the cloud services at any time, as stated in the ”Architecture of Managing Clouds” [2], Study Group Report of Cloud Computing [3], and others. For cloud computing, the quality and reliability of the services become an important aspect, as customers have no direct influence on the services. Therefore Service Level Agreements are fundamental to an effective cloud utilization and especially business customers need them to ensure risks and service qualities are prevented respectively provided in the way they want. For this purpose, the expected service qualities are documented legally binding in contracts between provider and customer. Due to significant variation in consumer needs, SLAs have to be created individually by a negotiation process. The confirmed SLAs serve as a basis for compliance and monitoring of the QoS. Due to the dynamic cloud character, the QoS attributes must be monitored and managed consistently [4]. In order to describe the QoS, metrics and key performance indicators (KPI) are used. These must exactly represent the actual service expectations and requirements, and correspond to both customer as well as provider. In addition to this QoS attributes representation, an SLA includes a general section, in which roles and responsibilities, costs, etc. are listed. The aim of this paper is to propose various possible KPIs for cloud SLAs to facilitate an assist customers in the negotiation and generation of SLAs for cloud services. In addition, a general insight on SLA content and structure as well as monitoring and management is given. After discussing related work in Section II, Section III will give a brief introduction into SLA content und management. Following Section IV presents the Service Level Objectives for cloud computing and the corresponding KPIs. The conclusion is drawn in Section V. II. RELATED WORK As the usage of cloud service by companies continues to grow, the need for SLAs is increasing. NIST [5] has pointed out the necessity of SLAs, SLA management, definition of contracts, orientation of monitoring on Service Level Objects (SLOs) and how to enforce them. A basic discussion of SLA management and cloud architectures can be found in Service Level Agreements for Cloud Computing [6], but it is mainly concerned about SLA definitions and negotiations. In recent years, a significant amount of research has been performed on the standardization and creation of machine- readable formats. There are two major specification for de- scribing SLAs, WSAL [7] and WS-A [8]. The Web Service Agreement Language (WSAL) [7] was developed by IBM with the focus on performance and availability metrics. It has been mainly developed for Web services and the usage in other fields is questionable. It shows significant shortcomings regarding content as it was focused mainly on technical properties. WS- Agreement (WS-A) [8]. was developed by the Open Grid Forum in 2007. The newest update, which is based on the work of the European SLA@SOI project, was done in 2011. Although it has been enhanced within the SLA@SOI project [9], the development is unclear, because the SLA@SOI project developed its own format SLA(T), which is supported by the European IT industry. Although much research has been done in the direction of SLA formats, the contents of SLAs remain a further field for investigations. The fact that SLAs are always very scenario specific makes it difficult to generalize their contents. KPIs, 60 Copyright (c) IARIA, 2013. ISBN: 978-1-61208-292-9 EMERGING 2013 : The Fifth International Conference on Emerging Network Intelligence