SPECIFYING AND MONITORING GUARANTEES IN COMMERCIAL GRIDS THROUGH SLA

1. Akhil Sahai Sven Graupner Vijay Machiraju Aad van Moorsel Hewlett-Packard Laboratories SPECIFYING AND MONITORING GUARANTEES IN COMMERCIAL GRIDS THROUGH SLA IEEE/ACM International Symposium on Clustering Computing and the Grid 2003 Presented by: Yun Liaw

2. Outline • Introduction • SLA and the Grid • Grid Deployment Infrastructure • Grid Management Architecture • Specifying and Monitoring SLAs • Conclusions & Comments

3. Introduction • “Best effort” was a sufficient policy for committing resources in academic grid environments • But when we moving into a commercial space, some stricter guarantees must be hold • 2 Problems arises: • At any given point of time hundreds of SLA may exist, with large number of metrics to be observed • SLA needs formalize representation so that the SLA evaluation can be automated • For a given application context, multiple resource providers and consumers are involved • The SLA management system must have the ability (Grid Proxy) to combine the distributed states of SLAs, to provide a consolidated view in the embracing application context

4. SLA and the Grid • Negotiating a SLA is an exchange (protocol) of messages between user and provider, potentially involving some form of a middleman or broker • SNAP (Service Negotiation and Acquisition Protocol) [11] • Designed for distributed systems • Three types of supported SLA in SNAP: • Resource acquisition agreements (user’s right to use the resource) • Task submissions agreements (inform needed resources of the existence of a user’s task) • Task/resource binding agreement (enabling the task to consume and agreed quantity of a resource) • Not mentioned the quality aspect, and the maintenance of SLA for the life-span meaning • It is important to understand the SLA hosting environment • To understand how SLA may be specified and monitored [11] K. Czajkowski, et al., “SNAP: A Protocol for Negotiation of Service Level Agreements and Coordinated Resource Management in Distributed Systems,” JSSPP, 2002

5. Grid Deployment Infrastructure • HP’s UDC (Utility Data Center) : Farm • A programmable hosting environment for applications • Globus Resource Specification Language (RSL) • A language to specify the resources in a grid, including the resource topology • For UDC resource manager to configure resources • In order to protect different farminstances, two types of resourcesare virtualized for farms: • Network Resources • Storage Resources

6. RSL Example

7. Grid Management Architecture • OGSA Grid Conceptual Architecture: based on web services (.Net or J2EE based) SLA management needs: Factory and R & D services to find resources based on QoS requirements Life-cycle management and manageability services to collect measurement data Reliable invocation for controlling resources Notification to inform impacted parties

8. Grid Management Proxy • Grid Proxy: • Corresponding to a particular Grid deployment infrastructure • Interact with each other forming a Grid management proxy overlay • Protocols that grid community has agreed on proxy communication • GRAAP: Grid Resource Allocation Management • GIS: geographic Information System • GASS: Grid Application Support System • GSI: Grid Security Infrastructure

9. SLA Definition • Purpose • The reasons behind the creation of the SLA • Parties • Parties involved in the SLA and their respective roles • Validity Period • The valid time of this SLA • Scope • The service scope covered in this SLA • Restrictions • The necessary steps to be taken for the requested service levels to be provided • Service Level Objectives • The service level that both users and the provider agreed on

10. SLA Definition (cont’d) • Service Level Indicators • The means by which these levels can be measured • Penalties • Describing what happens in case the service provider is unable to meet the SLO • Optional services • Services that are not normally required by the user, but may be an exception • Exclusions • Specifies what is not covered in the SLA • Administration • Describe the processes created in the SLA to meet and measure its objectives

11. SLA specification • An SLA is specified over a set of data that is measurable • Date constraint (start date, end date, nextEvalDate) • SLOs • Day-time constraint • MeasuredItems: Set of clauses based on measured data • Contains many items • evalWhen: the trigger time of this SLO evaluation • evalOn: Determine how the sample data is computed for the evaluation • evalFunc: the mathematical function that is expressible in terms of its inputs and logic

12. SLA specification • Example Scenario: • SLO clause: • At month-end, the availability of the farm allocated to the user myASP.com, measured on the myUDC.com from Mon-Fri from 9AM-5PM should be at least 99.9%

13. SLA Monitoring

14. SLA Measurement Protocol • Init: from measurement proxy to evaluate proxy • Request: The evaluator site decides the exact measurement spec and send to the measurement proxy • Agreement: The measurement proxy sends this message if it agrees to the request to the evaluator • Start: message from the evaluator to commence the report • Report: actual measurement report • Close: termination

15. Conclusions and Comments • Conclusions: • Applying grid model to commercial environmentrequires specification, monitoring and assurance of SLA • Define specification language and framework to monitoring • Comments: • No implementation detail • Waving hands