Virtualization In Cloud Computing

Published Date: 02 Nov 2017

Shubham Sidana

USICT,Guru Gobind Singh Indraprastha University

Sector - 16C Dwarka, Delhi - 110078, India

[email protected]

Abstract� Cloud computing is a way to run your business in a better way. Instead of running applications themselves, these business organisations run it on a shared data center. The term "cloud" is borrowed from telephony from those telecommunications companies, who until 1990s primarily offered point-to-point dedicated data circuits, began to offer Virtual private network services with almost same quality of service but it costs very less. Cloud computing stretches this boundary, it covers servers and network infrastructure also. Cloud computing claims to reduce cost greatly and capital expenditure is reduced to operational expenditure. The independence provided in device and location enable users to access systems using a web browser unconcerned of their location or what device they are using.

Keywords� Cloud Computing; Cloud; Virtualization; Hypervisors; Resiliency; Multitenancy;

I. INTRODUCTION

Cloud computing is an fast growing area that affects IT infrastructure, network services, and applications. In this we introduces various aspects of cloud computing, including its logics, underlying models, and infrastructures. Also we will provide details about some of the specifically used technologies and scenarios.

The term "cloud computing" has different definitions for professionals of IT, depending upon their own point of view and their own products and services. As with all emerging areas, real-world deployments and customer success stories will generate a better understanding of the term. The National Institute of Standards and Technology (NIST) definition of Cloud computing is as follows:

"Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (for example, networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction."[1]

Fig.1 Six computing paradigms (adapted from [2])

As In 1st phase, many users shared powerful mainframe computers using dummy terminals. In 2nd phase, PCs which are stand-alone became powerful enough to meet the majority of users� needs. In 3rd phase, servers, laptops, and PCs were connected together through local networks to share resources and increase performance. In 4th phase, global network is formed by connecting one local network to other local networks such as the Internet to utilize remote applications and resources. In 5th phase, grid computing provided shared storage and computing power through a distributed computing system. In 6th phase, cloud computing further provides shared resources on the Internet in a simple and scalable way.[2]

II. CLOUD COMPUTING BACKGROUND

A. Cloud Computing Features: [3]

The following is the list of characteristics of a cloud-computing environment. All characteristics may not be present in a specific cloud solution:

� On demand: Cloud Services are not permanent parts of your IT infrastructure, because you invoke them only when you need them�which is a significant advantage for cloud use in IT industries. With cloud services there is no need to have dedicated resources waiting to be used, as is the case with internal services.

� Elasticity and scalability: Cloud computing gives you the ability to expand and reduce resources according to your specific service requirement. For example, you may need a large number of server resources for the duration of a specific task. You can then release these server resources after you complete your task.

� Resiliency: The resiliency of a cloud service offering can completely isolate the failure of server and storage resources from cloud users. Work is migrated to a different physical resource in the cloud with or without user awareness and intervention.

� Pay-per-use: You pay for cloud services only when you use them, either for the short term (for example, for CPU time) or for a longer duration (for example, for cloud-based storage or vault services).

� Multitenancy: Public cloud services providers often can host the cloud services for multiple users within the same infrastructure. Server and storage isolation may be physical or virtual�depending upon the specific user requirements.

� Workload movement: This characteristic is related to resiliency and cost considerations. Here, cloud-computing providers can migrate workloads across servers�both inside the data center and across data centers (even in a different geographic area). This migration might be necessitated by cost (less expensive to run a workload in a data center in another country based on time of day or power requirements) or efficiency considerations (for example, network bandwidth). A third reason could be regulatory considerations for certain types of workloads.

B. Virtualization in Cloud Computing: [3]

It can be argued to good effect that cloud computing has accelerated because of the popularity and adoption of virtualization, specifically server virtualization. So what is virtualization? Here, virtualization software is used to run multiple Virtual Machines (VMs) on a single physical server to provide the same functions as multiple physical machines. Known as a hypervisor, the virtualization software performs the abstraction of the hardware to the individual VMs.

Virtualization is not new�it was first invented and popularized by IBM in the 1960s for running multiple software contexts on its mainframe computers. It regained popularity in the past decade in data centers because of server usage concerns. Data centers and web farms consisted of multiple physical servers. Measurement studies on these server farms noted that individual server usage was often as low as 15 percent for various reasons, including traffic loads and the nature of the applications (available, not always used fully), among others. The consequence of this server sprawl with low usage was large financial outlays for both CapEx and OpEx�extra machines and related power and cooling infrastructure and real estate.

A hypervisor is implemented on a server either directly running over the hardware (a Type 1 hypervisor) or running over an operating system (OS) (a Type 2 hypervisor). The hypervisor supports the running of multiple VMs and schedules the VMs along with providing them a unified and consistent access to the CPU, memory, and I/O resources on the physical machine. A VM typically runs an operating system and applications. The applications are not aware that they are running in a virtualized environment, so they do not need to be changed to run in such an environment. Figure 2 depicts these scenarios. The OS inside the VM may be virtualization�aware and require modifications to run over a hypervisor�a scheme known as paravirtualization (as opposed to full virtualization).

The following are some of the benefits of virtualization in a cloud-computing environment:

� Elasticity and scalability: Firing up and shutting down VMs involves less effort as opposed to bringing servers up or down.

� Workload migration: Through facilities such as live VM migration, you can carry out workload migration with much less effort as compared to workload migration across physical servers at different locations.

� Resiliency: You can isolate physical-server failure from user services through migration of VMs.

Fig. 2 Hypervisors in Virtualization (adapted from [3])

III. CLOUD TYPES

A. THE NIST MODEL:[4]

Most people separate cloud computing into two distinct sets of models:

� Deployment Models: This refers to the location and management of the cloud�s infrastructure.

� Service models: This consists of the particular types of type services that you can access on a cloud computing platform.

Fig. 3 The NIST cloud computing definitions (adapted from [4])

The NIST definition for the four deployment models is as follows:

� Public cloud: The public cloud infrastructure is available for public use alternatively for a large industry group and is owned by an organization selling cloud services.

� Private cloud: The private cloud infrastructure is operated for the exclusive use of an organization. The cloud may be managed by that organization or a third party. Private clouds may be either on- or off-premises.

� Hybrid cloud: A hybrid cloud combines multiple clouds (private, community of public) where those clouds retain their unique identities, but are bound together as a unit. A hybrid cloud may offer standardized or proprietary access to data and applications, as well as application portability.

� Community Cloud: A community cloud is one where the cloud has been organized to serve a common function or purpose. It may be for one organization or for several organizations, but they share common concerns such as their mission, policies, security, regulatory compliance needs, and so on. A community cloud may be managed by the constituent organization(s) or by a third party.

Three service types have been universally accepted:

� Infrastructure as a Service: Iaas provides virtual machines, virtual storage, virtual infrastructure, and other hardware assets as resources that clients can provision. The IaaS service provider manages all the infrastructure, while the client is responsible for all other aspects of the deployment. This can include the operating system, applications, and user interactions with the system. Examples are Amazon Elastic Compute Cloud (EC2), Eucalyptus, GoGrid, FlexiScale, Linode, RackSpace Cloud, Terremark etc.

� Platform as a Service: Paas provides virtual machines, operating systems, applications, services, development frameworks, transactions, and control structures. The client can deploy its applications on the cloud infrastructure or use applications that were programmed using languages and tools that are supported by the PaaS service provider. The services provider manages the cloud infrastructure, the operating systems, and the enabling software. The client is responsible for installing and managing the application that it is deploying. Examples are Force.com, GoGrid CloudCenter, Google AppEngine, Windows Azure Platform etc.

� Software as a Service: SaaS is a complete operating environment with applications, management, and the user interface. In the SaaS model, the application is provided to the client through a thin client interface (a browser, usually), and the customer�s responsibility begins and ends with entering and managing its data and user interaction. Everything from the application down to the infrastructure is the vendor�s responsibility. Examples are GoogleApps, Oracle On Demand, Salesforce.com, SQL Azure etc.

B. THE CLOUD CUBE MODEL:[5]

Fig. 4 The Jericho Forum�s Cloud Cube Model (adapted from [5])

The Four dimensions of the Cloud Cube model are shown in Fig. 4 and listed here:

� Physical location of the data: Internal (I)/External (E) determines your organization�s boundaries.

� Ownership: Proprietary (P)/ Open (O) is a measure of not only the technology ownership, but of interoperability, ease of data transfer, and degree of vendor application lock-in.

� Security boundary: Perimeterised (Per)/ De-perimeterised (D-p) is a measure of whether the operation is inside or outside the security boundary or network firewall.

� Sourcing: Insourced or Outsourced means whether the service is provided by the customer or the service provider.

IV. COMPARISION OF SOME POPULAR CLOUD SERVICE PROVIDERS

A. AMAZON EC2 (IAAS)

Table 1. Amazon EC2 characteristics[8]

S. No. LEVEL FOUND CHARACTERISTICS

1. Service IaaS

2. License Proprietary base framework

3. User group Corporate use

4. Payment Pay-per-use

5. Agreements SLA (incl. compensation)

6. Security PKI

7. Standards Public API

8. Openness Moderate

9. Supported OSs Non-preconf. Or prec. With Linux, Windows Server or OpenSolaris

10. Supported Applications/frameworks Non-prec. Or prec. With databases e.g. MySQL, Oracle; batch processing, e.g. Hadoop; web hosting e.g. Apache HTTP, IIS/Asp.Net

11. Dev. Tools Command-line tools, developer API

12. Virtualization Xen

B. MICROSOFT AZURE:

Table 2. Microsoft Azure Characteristics[9]

S.NO. LEVEL FOUND CHARACTERISTICS

1. Service PaaS

2. License Proprietary

3. User group Corporate Use

4. Payment Pay-per-use, free promotion offers

5. Agreements SLA

6. Security Unknown

7. Standards Supports SOAP and REST API [6]

8. Openness Basic

9. Supported languages/env. .NET, PHP

10. Supported OSs Windows

11. Supported applications/frameworks Live Services, MS .Net Services, MS SQL, Services, MS SharePoint, and MS Dynamics CRM Services

C. GOOGLE APPS:

Table 3. Google Apps. Characteristics[7]

S.NO. LEVEL FOUND CHARACTERISTICS

1. Service SaaS

2. License Proprietary

3. User group Corporate and Private use

4. Payment Free (private use), 50$ per account per year (corporate use)

5. Agreements No SLA (Private); SLA (corporate)

6. Security HTTPS/SSL

7. Standards No standards (Single-sign-on API for corporate use

8. Openness Moderate

9. Domain Office suite, incl. email, calendar, etc.

V. CLOUD COMPUTING CHALLENGES

Though cloud computing has a number of benefits, there are some challenges as addressed in [10]

� Performance: The major issue in performance can be for some intensive transaction-oriented and other data-intensive applications, in which cloud computing may lack adequate performance. Also, users who are at a long distance from cloud providers may experience high latency and delays.

� Security and Privacy: Companies are still concerned about security when using cloud computing. Customers are worried about the vulnerability to attacks, when information and critical IT resources are outside the firewall. The solution for security assumes that cloud computing providers follow some standards to take of it.

� Control: Some IT departments are concerned because cloud computing providers have a full control of the platforms. Cloud computing providers typically do not design platforms for specific companies and their business practices.

� Bandwidth Costs: With cloud computing, companies can save money on hardware and software; however they could incur higher network bandwidth charges. Bandwidth cost may be low for smaller Internet-based applications, which are not data intensive, but could significantly grow for data-intensive applications.

� Reliability: Cloud computing still does not always offer round-the-clock reliability. There were cases where cloud computing services suffered a few-hours outages.

VI. CONCLUSIONS AND FUTURE

In summary, cloud computing is definitely a type of computing paradigm/architecture that will remain for a long time to come. In the near future, cloud computing can emerge in various directions. One possible scenario for the future is that an enterprise may use a distributed hybrid cloud as illustrated in Fig. 5

According to this scenario, the enterprise will use the core applications on its private cloud, while some other applications will be distributed on several private clouds, which are optimized for specific applications.

Fig. 5 Distributed Hybrid Cloud Architecture (adapted from [11])