Cloud Computing intro

1. CLOUD COMPUTING
AN OVERVIEW &
QUALITY OF SERVICE
University of Manitoba
Department of Computer Science
Hamzeh Khazaei
Jan 28, 2010

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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

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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

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Computing Paradigm Shift

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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

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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
 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

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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

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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

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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

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High Level Architecture of
QoS

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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

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Some Important Questions regarding
Service Performance:
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?

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An Example Queuing Model

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Cluster, Grid and Cloud: Google trend

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Thank You !!!
Any Question?