Cloud Computing_ Intro - University of Manitoba - Department of

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					                CLOUD COMPUTING
                 AN OVERVIEW &
               QUALITY OF SERVICE

                   University of Manitoba
               Department of Computer Science



Jan 28, 2010               Hamzeh Khazaei
        Cloud Computing - Definition
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           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
        Cloud computing - Characteristics
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           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
        Computing Paradigm Shift
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        Cloud Computing - Some terms
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           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
        Cloud Computing Model
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        Cloud Computing Framework
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        Cloud Computing Architecture
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        Commercial clouds
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         Public, Private and Hybrid clouds
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         Quality of Service
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            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
         Service Level Agreement, SLA
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            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
         QoS requirements for a Cloud - ideal
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            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
         QoS requirements for a Cloud - ideal
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            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
         High Level Architecture of QoS
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         Service Performance and Analysis in Cloud Computing
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            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
         Some Important Questions regarding
         Service Performance:
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         1.   For a given arrival rate of requests and given service
              rate what level of QoS can be guaranteed?
         2.   What is the minimal service rate for a given percentile
              of the response time and a given service arrival rate?
         3.   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?
         An Example Queuing Model
18 /20
         Cluster, Grid and Cloud: Google trend
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20 /20




         Thank You !!!

         Any Question?

				
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