[ijcst-v3i6p18]: yogesh ghorpade, tajuddin bennur, dr. h. s. acharya, dr. r. kamatchi

International Journal of Computer Science Trends and Technology (IJCST) – Volume 3 Issue 6, Nov-Dec 2015

ISSN: 2347-8578 www.ijcstjournal.org 09

RESEARCH ARTICLE OPEN ACCESS

Server Virtualization Implementation: An Experimental

Study for Cost Effective and Green Computing Approach

towards Educational Infrastructure Management Yogesh Ghorpade [1], Tajuddin Bennur [2], Dr. H. S. Acharya [3]

Dr. R. Kamatchi [4] Research Scholar [1]

Department of Computer Science, Bharathiar University, Coimbatore

Tanil Nadu

Assistant Professor [2], Professor [3] Department of Computer Sciecne

Allana Institute of Management Sciences, Pune India

ABSTRACT Nowadays the IT world is going with use of virtualization technology in various aspects such as lab

experiments, clustering, parallel processing, distributed system etc. in educational system. Educational systems

are looking to v irtualization to reduce cost and increase security concern solutions as a suitable infrastructure

models. Relatively new to educational, the concept of v irtualization is proving itself in the business and

consumer world as “the next big thing.” The concept of virtualizat ion is very b road and can be applied to

devices, servers, operating systems, applications and even networks [7].

Entire classes or departments can be quickly and easily set up with new desktop devices and applications

because installation and configuration are done once, at the server, and duplicated as often as needed. Users can

log on to virtual desktops from any device in the network [11]. VMware provides an excellent platform for

deployment and VMM of Server Virtualizat ion. Academic Institutions can take benefit of this platform for use

in Laboratory to provide cost effective solutions. The infrastructure created can also be inte lligently used for

teaching networking concepts to students with the tremendous advantage of having everything at one place.

Providing a good platform where algorithms on parallel computing, distributed computing can be tested is a

necessity, which can be met with this type of infra -structure. The future research work in Server Virtualizat ion

will be carried in private cloud building and its virtual clustering [2].

In educat ional system the prob lem is how to ut ilize the old in frastructure to perform lab exercises which

requires h igh performance comput ing resources in educat ional system by the use o f Virtualization

environment. Th is paper is based on experimental procedure to obtain a specific model to implement a

standardized server virtualizat ion using VMware ESXi with VSphere on server side and VClient on client side.

This paper also focuses on green computing with the major factor Total Cost of Ownership (TCO).

Keywords: - Educational Infrastructure, Virtualization, Virtualization Environment, Virtual Machines, Green

Computing, Open Source, Clustering, TCO.

I. INTRODUCTION

The paper overcomes the prob lem of ut ilizing the

old in frastructure to perform lab exercises which

requires h igh performance computing resources

in educational system by the use of Virtu alizat ion

environment. It is based on experimental

procedure to obtain a specific model to implement

a standardized server virtualization using VMware

ESXi with VSphere on server side and VClient on

client side. In section 2 the paper covers the Life

cycle of virtualization with 4 phases. Section 3 and

4 covers the need and architectures of virtualizat ion

for the implementation purpose.

The user role, implementation procedure and its

outcome snapshots are discussed in section 5, 6 and

7 respectively. Evaluating Comparison of Total

Cost of Ownership (TCO) in section 8 is discussed.

This paper also focuses on green computing with

the major factors reusability and power

consumption of virtualized environment in section

9.

http://www.ijcstjournal.org/


ISSN: 2347-8578 www.ijcstjournal.org Page 110

II. LIFE CYCLE OF

VIRTUALIZATION

FIGURE 1: THE VIRTUALIZATION

LIFECYCLE

2.1 Requirement Management Phase

Virtualization teams use th is phase to understand

the current educat ional in frastructure requ irements

and the possible v irtualization targets and the

desired development and test env ironments.

Once in frastructural requirements have been

understood, the v irtualization leads then identify

the environment build strateg ies [8]. There are

always a few components in any env ironment

which have very s imple behav iors with low test

data management complexit ies and neg lig ib le

access constraints. These have low TCO and are

therefore not ideal targets for serv ice

virtualizat ion [6]. In educat ional system the

problem is how to utilize the o ld infrastructure to

perform lab exercises which requ ires high

performance computing resources [4].

2.2 Analysis and Design Phase

Based on the requ irements gathered from the

prev ious phase, the v irtualizat ion teams plan and

document the p rocess for v irtualizat ion

in frastructure in the analysis and des ign phase.

Analysed the laborato ry pract ical work to be

virtualized as per the requ ired s kills to balance

the infrastructural resources.

In th is phase, v irtualizat ion teams focus on

applicat ions identified for v irtualizat ion and their

associated funct ionalit ies. For linking the

funct ionalities to the app licat ions, v irtualizat ion

teams use a variety of arch itectu ral design .

Virtualizat ion teams must ensure that they use

valid input & output pairs fo r all scenarios in a

given virtual environment.

vCenter Server is a crit ical app licat ion fo r

managing your v irtual in frastructure. Its

implementat ion should be carefu lly des igned and

executed to ensure availability and data

protect ion. When d iscussing the deployment o f

vCenter Server and its components, the

fo llowing questions are among the most common

questions to ask:

* How much hardware do I need to power

vCenter Server?

* Which database server should I use with

vCenter Server?

* How do I p repare vCenter Server fo r d isaster

recovery?

* Should I run vCenter Server in a VM? [16].

2.3 Implementation Phase

The implementat ion phase invo lves the creat ion

of v irtual in frastructural environment fo r

fu lfillment o f educat ional infrastructural

requ irement. Various components of vSphere are

properly dep loyed to create v irtual env ironments.

It also invo lves implementat ion o f the

virtualizat ion strategy with selected tools [10].

2.4 Deploy and Manage Phase

Used fo r dep loy ing and managing the v irtual

applicat ions and refin ing requ irements for the

next iteration . Deploy ing VMware vSphere is

more than just v irtualizing servers. The effects o f

storage, networking , and security in a vSphere

deployment are as equally sign ificant as they are

with the physical servers themselves. As a result

of th is b road impact on numerous facets o f your

organ izat ion 's IT, the process of p lann ing the

vSphere dep loyment becomes even more

important. Without the appropriate p lann ing fo r

your vSphere implementation , you run the ris k o f

configuration prob lems, instab ility,

incompat ib ilities, and d imin ished financial

impact.

Your plann ing process for a vSphere dep loyment

involves answering a number of questions

* What types of servers will I use fo r the

underlying physical hardware?

* What kinds of storage will I use, and how will

I connect that storage to my servers?

* How will the networking be configured?

vSphere vCente r is requ ired to be properly

deployed to manage the vSphere components

such as ESXi (host), VM vClient and resources

like data store, memory, etc. with it [16].




III. NEED OF EXPERIMENTAL

DESIGN OF SERVER

VIRTUALIZATION?

The previous research paper was based upon the

purpose and need of designing of server

virtualizat ion which includes all the basics terms,

factors, structural overview etc. [2].

IV. VIRTUALIZATION

ARCHITECTURE AND POLICY

FOR IMPLEMENTING OF

PLATFORM

The implementation of virtualizat ion technology

using VMware requires different phases as per the

resource availability. High resource availab ility in

educational scenario about virtualizat ion is lacking.

Therefore the implementation building is done with

the help of available old resources.

In the figure 2 vSphere arch itechture the required

components to build the vCenter is shown with

management scope. The functionality within

vCenter server and Database server ig given.

FIGURE 2: VSPHERE ARCHITECTURE AND SCOPE

[16].

a. Integrated Cluster Architecture

The below arch itecture in figure 3 gives an overall

structural design and basic resource availability.

Integrated architecture is the combination of

various clusters link together to the vCenter Cluster

controller. Th is single cluster is the combination of

various Virtual Machine (VM) nodes connected

with single ESXi. Each ESXi uses either Type 1 or

Type 2 Machines within the provided Lab with

available Datastore. This VM are accessed via

vClient software by either old desktop or thin client

having low resources. This experiment is Design

in AIMS lab 5 with 1 Gbps Ethernet cable and 100

mbps speed switches. The vCenter Cluster

Controller plays a main role in this virtualizat ion

infrastructure implementation.




FIGURE 3: INTEGRATED CLUSTER ARCHITECTURE

4.2 Single Cluster Architecture

The architecture in figure 4 is based upon detailed

requirement of Software and Hardware resources

for designing of single cluster which includes

VMware components, operating system, desktop

/thin client, based upon Hypervisor, Server

machine, Datastore etc. The information about

Processor type, family, total cores, hyper threading

etc. is useful for making configuration of VM as

per the required resources.

One of the operating system within the cluster in

ESXi is used for user management and database

name creation by installing Windows server 2008.

If new machines are not availab le for vClient then

system admin istrator goes for old machines and old

machines are not available then they go for thin

clients with low resources availability. For different

subject labs the system administrator installs

different operating system and applications as per

the requirement e.g. Linux, Windows, JDK,

MYSQL, etc. Each ESXi as shown in arch itecture

supports 4 VM’s within a cluster.

FIGURE 4: SINGLE CLUSTER ARCHITECTURE

4.3 Storage Architecture

The main role of Datastore lies within the Storage

architecture for the purpose of storage access via

client or ESXi. The datastore in the experiment is

implemented as per the resource availability within




the server and new or old desktops. Thus the VM

client’s datastore can be categorized on the basis of

the storage available as shown in Figure 5. That

means if thin clients are used the datastore will be

available through ESXi or vCenter. The role of

datastore in vCenter is for Server OS, VM, active

directory, DHCP, etc. [5].

FIGURE 5: STORAGE ARCHITECTURE

4.4 IP addressing Policy

FIGURE 6: IP ADDRESSING POLICY FOR VIRTUALIZATION IMPLEMENTATION

IP address subnetting procedure without VLAN is carried in the experiment as shown in figure 6. Different IP

address ranges are assigned for vCenter, ESXi, VM etc. As per the user requirement the class is assigned and

subnetted. The auto configuration of IP addressing can be done through DHCP in active directory in windows

server 2008 VM. Further VLAN and switching techniques can be carried in future experimental study.




V. USER ROLES

Users Role Systems Tasks

System

Administrator VMware vCenter

User management

Integrating of ESXi

vCenter, ESXi and VM deployment

Teacher / Trainer

Vsphere ESXi

User management

Integrating of VM

VM deployment

Application installation

Students /

Employees

VM vClient

VM access

Application access

TABLE 1: USER WISE T ASK DETAILS

Roles are distributed according to their tasks

obtained as shown in the table.1. The different

categories are set for defining of ro les by which a

proper management policy is maintained and well

implementation and use of virtualization plat form

takes place. Primary user is System administrator

whose main role is to control the vCenter with all

the safety and security control measures. He is also

responsible for deployment of VMware

components and applications. Time spent on

routine System administrative tasks are Backup and

data protection, Application availab ility, Ability to

respond to changing educational needs,

Organizational continuity preparedness and

Organization profitability and growth rate.

The secondary role is done by the Teacher or

Trainer for creating of several or individual subject

lab with user management. The student role is the

access only towards VM and applicat ions from any

desktop or thin client.

VI. PROCEDURE OF IMPLEMENTATION

6.1 Deploying vCenter Server Instance

Installation of core components with a single virtual machine. The components are vCenter Single Sign -On,

vSphere Web Client, vCenter Inventory Service and vCenter Server.




FIGURE 7: IMPLEMENTATION PROCEDURE

Prerequisites for vCenter Server are shown in appendix 2.

We will deploy a single vCenter Server instance that meets the requirements for most educational institutes,

paying careful consideration to the various steps and configurations.

6.1.1 vCenter Single Sign-On

6.1.2 vSphere Web Client Install




6.1.3 vCenter Inventory Service

6.1.4 vCenter Server




6.2 Deploying vSphere ESXi 5.5

ESXi Server 5.5 is the bare metal hypervisor that will run our VMs and may be one of several servers you wish

to build into a cluster managed by vCenter server to provide HA, DRS and vMotion features for VMs. The ESXi

server installation is straightforward, at this initial stage all we need to do is get the hypervisor installed, give it

an IP address and password before proceeding with the various steps for the vCenter Server install. Prerequisites

for vSphere 5.5 are shown in appendix 3.




VII. SNAPSHOTS OF IMPLEMENTED OF VIRTUALIZED SCENARIO

FIGURE 8: STORAGE SETUP




FIGURE 9: NETWORK CONFIGURATION

FIGURE 10: VIRTUAL MACHINE SETUP AND CLUSTER SUMMARY

VIII. COST COMPARISON

The main problem is to determine resource demand

of each application and to allocate resources in the

most efficient way. To deal with this problem the

authors apply an economic framework: the system

allocates resources in a way that maximizes the

"profit" by balancing the cost of each resource unit

against the estimated utility that is gained from

allocating that resource unit to a service [17].

The basic parameters, structural design for cost

comparison between virtualized and non-

virtualized environment have been discussed in our

previous research paper [2]. The additional

informat ion of cost for implementation of this

experiment is given in below table 2.




Non-Virtualization Virtualization

Parameters Cost % Parameters Cost %

Hardware 150000 89 Hardware 80000 84

Software 10000 6 Software 10000 11

Support (Staff, external

providers, contractors)

5000 3 Support (Staff, external providers,

contractors)

2000 2

Network Communication 3000 2 Network Communication 3000 3

Total 168000 100 Total 95000 100

Note:- Virtualization->Considering 1 Cluster=5 machines (4 VM & 1ESXi)

Non-Virtualization->Considering 5 machines

Cost is given in Rs(INR) TABLE 2: COMPARISON OF TCO BETWEEN NON VIRTUALIZED AND NON-VIRTUALIZED (GARTNER

RESEARCH, 2007)

FIGURE 11: BAR CHART FOR COST COMPARISION

FIGURE 12: PIE CHART FOR COMPARISION OF TCO


International Journal of Computer Science Trends and Technology (I JCST) – Volume 3 Issue 6 , Nov-Dec 2015


IX. GREEN COMPUTING

The basic parameters and power consumption for Green

computing have been discussed in our prev ious research paper

[2].

a. Managing Energy and Server Resources in

Virtualized Environment:

The main resources are used in ESXi and vCenter Server for

the management of Virtualized Environment v ia Thin clients

or old desktops (which have less resource). In educational

organization according to the available budget and current

QoS requirements, i.e. balancing cost of resource usage

(energy cost) and benefit gained due to usage of this resource.

This enables a virtualized environment to improve the energy

efficiency under fluctuating workload, dynamically match

load and power consumption, and respond gracefully to

resource shortages [17].

b. Ways to reduce IT Load:

Since powering the IT load in educational infrastructure is

such a large portion of the overall electricity cost in a

Virtualized Environment, reduction of this load must be a

primary consideration in any energy efficiency in itiative.

There are a number o f ways to reduce this load including the

following:

• Virtualize or consolidate servers

• Reuse servers for ESXi which are no longer in use

• Enable power management

• Replace inefficient servers

• Power down servers when not in use

X. BENEFIT OF VIRTUALIZATION

There are number of benefits in educational organizations of

virtualizat ion. It reduces operational complexity, maintains

flexib ility in selecting software and hardware p latforms and

product vendors. It also increases flexibility in managing

different virtual environments. Some of the benefits of

virtualization are:

*Server and application consolidation

Virtual machines are used to consolidate the workloads of

under-utilized servers on to fewer machines , perhaps a single

machine. It includes savings on hardware and software

resources, management, and administration of the server

infrastructure. In virtualization the execution of applications is

well served by virtual machines. It consolidates various

heterogeneous applications running on single platform for

better utilization of resources.

*Multiple execution environments and Resource sharing

Different operating system and various applications are

accessed by students on different desktops or thin clients via

this platform. Virtual machines also provide hardware

configuration such as SCSI, Ethernet, CD / DVD drives

devices. It can also be used to simulate networks of

independent computers. In virtualization ESXi platform run

multip le operating systems simultaneously having different

versions like in Linux Fedora 11, 12 etc., or even different

vendors like Linux, Windows etc. Virtualizat ion empowers

the operating systems, applications to run on shared memory

multiprocessors. It also shares Datastore, network devices and

many more resources.

*Debugging and Performance

Virtualizat ion in VM enables powerful debugging and

performance monitoring tools. It also provides fault and error

regulation by isolating applications and services on which

they run [3]. Virtualization handles tasks such as system

migrat ion, backup, and recovery easier and more manageable.

Virtualizat ion is a great tool for research in academic

experiments. They provide isolation, and encapsulate the

entire state of a running system. Since we can save the state,

examine, modify and reload it. Hence it provides an

abstraction of the workload being run [12].

XI. CONCLUSION

-After implementat ion o f virtualizat ion p latfo rm the TCO

is reduced by 43%. This number shows that the cost

efficiency in educational o rgan ization is well ut ilized for

ROI.

-The Green Comput ing leads to manage power

consumption by reducing carbon footprints. The o ld

resources o f the educat ional o rgan ization in Virtualized

Environment are reused.

-Built app licat ions on v irtual machine as per the p ract ical

domain scenario and p roper implementation of operating

systems as per the categorization of practical labs.

-Configurat ion and dep loyment methodology for the proper

implementat ion o f vSphere and related required

components for built of educational platform is achieved.

-Implemented proper authent icat ion , authorization and

privileges with accountability are managed.

-Benefits of virtualized environment are adopted.

ACKNOWLEDGEMENT

Our sincere thanks to Dr. H. S. Acharya for the accurate

research coordination, Dr. R. Ganesan, Prof. Jawed Khan for

resource utilization and Allana Institute of Management




Sciences: MCA Department, Pune for their constant

encouragement.

REFERENCES

[1] DELL SOFTWARE “Top 10 Virtualization

Automation Tips fo r Infrastructure and Operat ions

Administrators”, Whitepaper-VirtualAutoTips-

InfraOpAdmin-US-KS-23761.

[2] GHORPADE YOGESH, S. GHORPADE,

TAJUDDIN BENNUR, H.S.ACHARYA “Server

Virtualizat ion. A Cost Effective and Green

Computing Approach towards Educational

Infrastructure Management”. International

Conference on Cloud Computing and Computer

Science IRAJ. ISBN: 978-81-927147-2-1(May

2013).

[3] GHORPADE YOGESH, H.S.ACHARYA, “Data

Mining Performance Parameters of Client Machine

under a Flat Network and Subnetted Network”.2nd

National Conference on Data Min ing. ISBN: 978-93-

82880-25-7 (January 2013).

[4] GHORPADE YOGESH, M. SHAIKH, and

H.S.ACHARYA “Educational Infrastructure

Management: PARAVIRTUALIZATION in the

classroom”. Allana Management Journal of

Research. ISSN 2231-0290, (July-Dec 2012).

[5] GHORPADE YOGESH, Networking Textbook on

“Data Communication and Computer Network”

DCCN SELF PUBLICATION PUNE ISBN: 978-93-

5137-573-9, (Jan 2013).

[6] Hattangadi Gaurish Vijay, “A Pract itioner’s

Approach to Successfully Implementing Service

Virtualization”, White Paper Infosys, Sep 2011.

[7] IBM Global Education White Paper, “Virtualization

in Education”, Oct-07.

[8] ICCS, “Deploying Virtual Infrastructure on Standard

Operating Systems”, Iccs Whitepaper, IDEAS

Custom Consulting Services, Jan 2008.

[9] JEFF DANIELS, “Server Virtualization Architecture

and Implementation”, Crossroads

www.acm.org/crossroads, Vol. 16, No.1, 2009.

[10] LEJA CHRISTINE, Implementing Server

Virtualizat ion At South western Illinois College

(Case Study), Implementing Server Virtualizat ion –

SWIC Case Study, 1/15/2010.

[11] THE CDW G Edtech magazine White paper, “Client

Virtualization for Education”.

[12] MUEEN UDDIN, AZIZAH ABDUL RAHMAN,

“Implementing Virtualizat ion A six-step guide to

virtualizat ion implementation for a more efficient,

reliable, and flexible data center”, (IJACSA)

International Journal of Advanced Computer Science

and Applications, Vol. 2, No.1, January 2011.

[13] VMWARE FEATURE SUPPORT, “Installing and

configuring the ESXi Virtualization Software”,

www.vmware.com/pdf/vsphere4/r41/vsp_41_esxi_i

_vc_setup_guide.pdf.

[14] WALKER GROUP, “Design & Implementation The

Walker Group”, thewalkergroup.com/itmanagement/

design implementation/, 24 Dec 2014.

[15] vSphere Components, vSphere 4.1 - ESX and

vCenter > Getting Started with ESX > Managing

Multiple Hosts with vCenter Server,

https://pubs.vmware.com

[16] LOW E SCOTT and NICK MARSHALL with Forbes

Guthrie, Matt Liebowitz Atwell, “Mastering VMware

vSphere 5.5”,Edition 2013, Ch-2 “Planning and

installing VMware ESXi”, November 2013.

[17] Beloglazov Anton, Buyya Rajkumar, Young Choon

Lee, and Albert Zomaya, “A Taxonomy and Survey

of Energy-Efficient Data Centers and Cloud

Computing Systems”, Green Cloud Taxonomy, 2010.

[18] Gartner Research 2006-2007 IT Spending and

Staffing Report” - North America 5 March 2007 ID

Number: G00146284.

APPENDICES

Appendix 1

Checklist 1: Pre Checklist for Hardware, software and storage.

You can use the following worksheet to organize your

evaluation process

HARDWARE CHECKLIST: Comment

All hardware has been validated against the

VMware vSphere 5.5 Hardware

Compatibility List (HCL).

Each server has 1x 1GB or 2x 1GB network

cards connected to a common switch (this

will be configured as a network adaptor

team).

Each server has the required HBA/network

adaptor to access shared storage.

SOFTWARE CHECKLIST:

VMware vSphere/VMware ESXi installation

media is available.

VMware vCenter™ Server appliance is

downloaded.




VMware vSphere® Client™ is installed.

ESXi host 1 hostname.



Subnet, netmask and default gateway for

management network.


virtual machine network.


vMotion network.

STORAGE CHECKLIST:

All servers can see at least three common

available LUNs (or NFS exports).

Datastore 1 name.

Datastore 2 name.

Datastore 3 name.

Appendix 2

PREREQUIS ITES for vCenter 5.5 Comment

Deploy, and name accordingly, two W indows -

based virtual machines with two volumes each.

Assign a static IP address to both virtual

machines.

Confirm forward and reverse DNS resolution

of hostname and IP address on both virtual

machines.

Add the Windows virtual machines to the

Active Directory environment.

Confirm that virtual machine time is

synchronized with an Active Directory domain

controller.

On one virtual machine, install and configure

Microsoft SQL Server.

Create an empty database.

On the other virtual machine, create and name

an x64 ODBC data source name for the newly

created database.

Create an Active Directory domain account to

be used as the service account for running

vCenter Server.

Appendix 3

PREREQUIS ITES for vSphere ESXi 5.5 Comment

ESXi 5.5 will install and run only on servers

with 64-bit x86 CPUs.

ESXi 5.5 requires a host machine with at least

two cores.

ESXi 5.5 supports only LAHF and SAHF CPU

instructions.

ESXi 5.5 requires the NX/XD bit to be enabled

for the CPU in the BIOS.

ESXi requires a minimum of 4GB of physical

RAM. Provide at least 8GB of RAM to take

full advantage of ESXi features and run virtual

machines in typical production environments.

To support 64-b it virtual machines, support for

hardware virtualizat ion (Intel VT-x/AMD

RVI) must be enabled on x64 CPUs.

One or more Gigabit or 10Gb Ethernet

controllers. For a list of supported network

adapter models

AUTHORS PROFILE

Yogesh Ghorpade received M.C.A.

degree from University of Pune and

pursuing Ph.D. in the area of “Server

Virtualizat ion” from Bharatiar

University, Tamil Nadu. Currently he is

working as a Sen ior Trainer, at one of

the Corporate Organization. His main

areas of research interest are planning

and creation of Virtualization Infrastructure, deployment of

Virtualizat ion Infrastructure, HPC and Network Monitoring.

He has written 8 research papers in international and 2

research papers in national journals in computer category. One

of the papers is best rated in Academia Research open access

journal and excellent paper award in International Conference

(IRAJ). He has written several books in the field of

Networking, Information Security.

Tajuddin Bennur received M.C.A.

degree in 2009 from University of

Pune. Currently he is working as an

Assistant Professor, at Allana

Institute of Management Science,

Pune. He has 5 plus years academic

experience and also has hands on

experience in software development.

His main areas of research interest

are Virtualizat ion, Network

Monitoring and medical informat ics. He has written many

research papers in international and national journals in

medical informatics and virtualizat ion. He has also achieved

excellent paper award in International Conference (IRAJ).


[ijcst-v3i6p18]: yogesh ghorpade, tajuddin bennur, dr. h. s. acharya, dr. r. kamatchi

Documents

vmm of server virtualizat

parallel computing

distributed computing

educational systems

concept of virtualizat

distributed system

green computing approach

educat ional system