1.4 DESIRED FEATURES OF A CLOUD

Certain features of a cloud are essential to enable services that truly represent the cloud computing model and satisfy expectations of consumers, and cloud offerings must be

self-service,
per-usage metered and billed,
elastic, and
customizable.

1.4.1 Self-Service

Consumers of cloud computing services expect on-demand, nearly instant access to resources. To support this expectation, clouds must allow self-service access so that customers can request, customize, pay, and use services without intervention of human operators.

1.4.2 Per-Usage Metering and Billing

Cloud computing eliminates up-front commitment by users, allowing them to request and use only the necessary amount. Services must be priced on a short-term basis (e.g., by the hour), allowing users to release (and not pay for) resources as soon as they are not needed [5].

Clouds must implement features to allow efficient trading of services such as pricing, accounting, and billing.

Metering should be done accordingly for different types of service (e.g., storage, processing, and bandwidth) and usage promptly reported, thus providing greater transparency.

1.4.3 Elasticity

Cloud computing gives the illusion of infinite computing resources available on demand. Therefore users expect clouds to rapidly provide resources in any quantity at any time.

In particular, it is expected that the additional resources can be (a) provisioned, possibly automatically, when an application load increases and (b) released when load decreases (scale up and down).

1.4.4 Customization

Resources rented from the cloud must be highly customizable. In the case of infrastructure services, customization means allowing users to deploy specialized virtual appliances and to be given privileged (root) access to the virtual servers.

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2.1 VIRTUAL MACHINES PROVISIONING AND MANAGEABILITY

In this section, we will have an overview on the typical life cycle of VM and its major possible states of operation, which make the management and automation of VMs in virtual and cloud environments easier than in traditional computing environments As shown in Figure above, the cycle starts by a request delivered to the IT department, stating the requirement for creating a new server for a particular service. IT administration to start seeing the servers’ resource pool, matching these resources with the requirements, and starting the provision of the needed virtual machine. Once provisioned machine started, it is ready to provide the required service according to an SLA, or a time period after which the virtual is being released.

1.2 ROOTS OF CLOUD COMPUTING

We can track the roots of clouds computing by observing the advancement of several technologies, especially in hardware (virtualization, multi-core chips), Internet technologies (Web services, service-oriented architectures, Web 2.0), distributed computing (clusters, grids), and systems management (autonomic computing, data center automation). Below Figure shows the convergence of technology fields that significantly advanced and contributed to the advent of cloud computing. . We present a closer look at the technologies that form the base of cloud computing, with the aim of providing a clearer picture of the cloud ecosystem as a whole. 1.2.1 From Mainframes to Clouds 1.2.2 SOA, Web Services, Web 2.0, and Mashups 1.2.3 Grid Computing 1.2.4 Utility Computing 1.2.5 Hardware Virtualization 1.2.6 Virtual Appliances and the Open Virtualization Format 1.2.7 Autonomic Computing ______ Cloud computing has its roots in several technologies and developments, including virtualization, gr...

2.1.1 VM Provisioning Process

Steps to Provision VM. Here, we describe the common and normal steps of provisioning a virtual server: Firstly, you need to select a server from a pool of available servers (physical servers with enough capacity) along with the appropriate OS template you need to provision the virtual machine. Secondly, you need to load the appropriate software (operating system you selected in the previous step, device drivers, middleware, and theneeded applications for the service required). Thirdly, you need to customize and configure the machine (e.g., IP address, Gateway) to configure an associated network and storage resources. Finally, the virtual server is ready to start with its newly loaded software. These are the tasks required or being performed by an IT or a data center’s specialist to provision a particular virtual machine.

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