Cloud Computing An overview & Quality of Service

1. University of Manitoba Department of Computer Science Cloud Computing An overview & Quality of Service Jan 28, 2010 Hamzeh Khazaei

2. Cloud Computing - Definition • There is no unique and standard definition out there • However, it is generally accepted that CC refers to a new IT paradigm for users • One of those definitions: • Cloud computing is a style of computing paradigm in which typically real-time scalable resources such as files, data, software, hardware, and third party services can be accessible from a Web browser via the Internet to users

3. Cloud computing - Characteristics • Agility – On demand computing infrastructure • Linearly scalable – challenge • Reliability and fault tolerance • Self healing – Hot backups, etc • SLA driven – Policies on how quickly requests are processed • Multi-tenancy – Several customers share infrastructure, without compromising privacy and security of each of the customer’s data • Service-oriented – compose applications out of loosely coupled services. One service failure will not disrupt other services. Expose these services as API’s • Virtualized – decoupled from underlying hardware. Multiple applications can run in one computer • Data, Data, Data • Distributing, partitioning, security, and synchronization

4. Computing Paradigm Shift

5. Cloud Computing - Some terms • Term cloud is used as a metaphor for internet • Concept generally incorporates combinations of the following • Infrastructure as a service (IaaS) • Platform as a service (PaaS) • Software as a service(SaaS) • Not to be confused with • Grid Computing – a form of distributed computing • Cluster of loosely coupled, networked computers acting in concert to perform very large tasks • Utility Computing – packaging of computing resources such as computing power, storage, also a metered services • Autonomic computing – self managed

6. Cloud Computing Model

7. Cloud Computing Framework

8. Cloud Computing Architecture

9. Commercial clouds

10. Public, Private and Hybrid clouds

11. Quality of Service • Everything in cloud computing is delivered as service • So quality of service is inevitable • QoS has multiple aspects such as: • Response time • Throughput • Availability • Reliability • Security

12. Service Level Agreement, SLA • The SLA is a contract negotiated and agreed between a customer and a service provider • Service provider is required to execute service requests from a customer within negotiated quality of service requirements for a given price • Due to variable load, dynamically provisioning computing resources to meet an SLA and allow for an optimum resource utilization will not be an easy task

13. QoS requirements for a Cloud - ideal • The QoS must system be able to manage several simultaneous services with a specific response time limitation for each service • The QoS system must supply service differentiation in the service provider to the consumer – consumer category • The QoS system must support the grouping of interactions in sessions. • The QoS system should not require modification in the system software of the servers

14. QoS requirements for a Cloud - ideal • The QoS system should be easy to configure • The QoS system must be scalable to operate in both a single server and a cluster of servers • The QoS system must provide protection against overloads and low utilization • The QoS system may support dynamic negotiation of parameters

15. High Level Architecture of QoS

16. Service Performance and Analysis in Cloud Computing • For the commercial success of cloud computing the ability to deliver QoS guaranteed services is crucial • Clearly customers are more concerned about response time rather than other performance metrics • Usually customers are more inclined to the percentile of time in which they receive their services less than a given value • P-percentile: it means a given customer receives p% of his services less than a pre-defined time value in the SLA

17. Some Important Questions regarding Service Performance: • For a given arrival rate of requests and given service rate what level of QoS can be guaranteed? • What is the minimal service rate for a given percentile of the response time and a given service arrival rate? • How many number of customers can be supported so that a given percentile of the response time can be still guaranteed when service rate is given?

18. An Example Queuing Model

19. Cluster, Grid and Cloud: Google trend

20. Thank You !!! Any Question?