SPECIFYING AND MONITORING GUARANTEES IN COMMERCIAL

GRIDS THROUGH SLASven Graupner

Vijay Machiraju Aad van Moorsel

IEEE/ACM International Symposium on Clustering Computing and the Grid

2003

Akhil Sahai

Presented by: Yun Liaw

Hewlett-Packard Laboratories

Outline

Introduction SLA and the Grid Grid Deployment Infrastructure Grid Management Architecture Specifying and Monitoring SLAs Conclusions & Comments

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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

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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

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[11] K. Czajkowski, et al., “SNAP: A Protocol for Negotiation of Service Level Agreements and Coordinated Resource Management in Distributed Systems,” JSSPP, 2002

Grid Deployment Infrastructure

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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

RSL Example

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Grid Management Architecture7

•OGSA Grid Conceptual Architecture: based on web services (.Net or J2EE based)

SLA management needs:1.Factory and R & D services to find resources based on QoS requirements2.Life-cycle management and manageability services to collect measurement data3.Reliable invocation for controlling resources4.Notification to inform impacted parties

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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

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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

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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

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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

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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%

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SLA Monitoring

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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

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Conclusions and Comments

Conclusions: Applying grid model to commercial environment

requires specification, monitoring and assurance of SLA

Define specification language and framework to monitoring

Comments: No implementation detail Waving hands

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