Many of you have heard this question and have different thoughts on using virtualization in cloud. While some professionals say that virtualization is not mandatory for cloud and other say that Virtualization is the base for cloud. I am trying to answer the above question by providing a rationale for using virtualization in cloud.

Before entering into a debate, let me explain Virtualization concept in simple terminology.

Server Virtualization OS segregates the interaction between hardware and OS. This will help us to keep independent OSs above a single hardware. The resource management will be taken care by virtualization OS.

Resource pool is concepts inside the virtualization layer which will help to combine the resources (Memory and CPU) from multiple hardware's and show that as single unit to Guest OS (VM). Many virtualized servers can be added under one virtual cluster which will help us to have a larger resource pool. Larger Resource pool means we will have more number of GB's (RAM) and GHz (CPU). The resource allocation to resource pool will be based on the business and application requirement.

This diagram is simplified view for Virtualized Server. Virtualization OS sits above the Physical server hardware. Guest OS will reside above Virtualization OS and all those Guest OS will work independently like a separate physical server. Guest OS instance is also called as Virtual Machine (VM). Applications are hosted inside the guest OS (Virtual Machine) and it will work like normal physical servers. VM and its applications are not aware that they are virtually hosted. Users can access the application as per normal process.

IT infrastructure is using the virtualization technology to achieve more cost benefits as it will help to consolidate and optimize the resource utilization.

Some of the benefits of virtualization are listed below:

• High availability
• Rapid Provisioning
• Centralized management
• Secured between VM's (Server's)
• Pool of resources and effective resources management
• Effective server hardware utilization
• Easy Monitoring
• Add and remove the server hardware without downtime
• On-demand computing
• Scalability
• Elasticity

Cloud will have all of the above benefits along with Self-Provisioning, Automation and Metering & billing. Scalability, metering   and elasticity are the prime features in cloud model which will help to provide the "on demand" and "pay as you go" based cloud service. By stating that, virtualization covers maximum of cloud features thus its providing base for cloud. Virtualization is a major player in Private cloud and IaaS cloud delivery model.

This diagram depicts the cloud environment with multiple virtual servers and multiple corporate users. We can host many virtualized servers in cloud and it will provide the pool of resources to its users. Virtualization cluster and resource pool will help us to provide the distributed resource to VM's based on the requirement. The users can be from one or more Companies. The allocation/de-allocation of resources will happen automatically based on the request from user. The cloud environment is accessible over internet and it has high scalability and availability. The Cloud Billing is based on the required resources, availability level and SLA. Cloud user will pay only for what they have used or requested.

Companies movement towards cloud is to get major benefits like cost reduction and liability of IT infrastructure. Cloud service delivery model delivers the power of virtualization along with the additional features like self-provisioning, Internet accessibility and metering & billing. Virtualization needs to be leverage to build a perfect cost effective cloud infrastructure.

Recently I read a catchy statement from one article which is "Why buy a plane when you can just reserve a seat on a flight?" Recent days, this is the mind set of all the IT enabled companies and it will give an easy understanding on cloud computing. If you want me to explain this - "Why you need to buy a datacenter when you have option to reserve a server (IaaS)/Platform (PaaS)/Application (SaaS)?"  If the options are available to get the required services like IaaS,PaaS and SaaS then why do we need to own infrastructure which is a huge liability, from both CAPEX and OPEX, instead invest on the cloud were we could utilize the existing CAPEX and increase the OPEX for better and smarter infrastructure.

Now the following question arises: Is it possible to make a cloud environment without virtualization? The answer is yes, but how much benefit you will get and how it differs from the present scenario is the question. If we build a cloud without virtualization then it will only achieve the cost benefit using Application level consolidation, Self-Provisioning, and automation and metering& billing but this benefit is very modest compared to the Virtualized cloud environment. Virtualized cloud environment will provide the features like High availability, Rapid Provisioning, Centralized management, Pool of resources thus effective resources management, Effective server hardware utilization, Add and remove the server hardware without downtime, Scalability and Elasticity.

Sharing the recent survey information to understand the ratings of cloud and virtualization-CIO's view. Based on the Gartner survey of CIO's -2011, cloud computing placed at top in global ranking while virtualization placed in second place.  (http://www.gartner.com/it/page.jsp?id=1729814)

Also note that, whatever I have explained here is more related to server virtualization and we have other virtualization options like Storage, Network, application and desktop which will provide much more benefit to Virtualized cloud environment.

As you would have guessed correctly, my answer for "Is virtualization really a base for cloud?" is "yes" virtualization is base for cloud. I have explained the rationale behind my stand which would have given you more clarity and insight.