In today’s world many technocrats, DBAs, CIOs and CTOs are very concerned about the expenses bill on hardware procurements and also on the optimal , consolidated and cost-effective usage of the same.  I will try to get inside the problem with the help virtualization as a solution and try to build a series of blogs on virtualization (with special reference to vBlock and Oracle) . In this particular blog I will try to address the basic concepts of virtualization and its comparison with the traditional physical server architecture.

Virtualization Traditionally, operating systems and software run on a physical server. Many challenges exist in running a large number of physical servers in a typical datacenter. To run this type of infrastructure may not be efficient and cost effective in the long run. To plan and spend for the maintenance cost of this type of very large infrastructure (square footage, rack space, power, cooling, cabling, and server provisioning) are some of the problems that IT staff  and their managements are addressing on a daily basis.

Typically, there exists a one to one correspondence between a physical computer and the software that it runs. This relationship leaves most of the resources of the computers hugely idle and underutilized, leaving between only 5–15 percent (approx.) of physical server capacity in use. The cost of the space and power required to house, run and keep these systems cool can be expensive.

It is very tedious to provision physical servers as it is a time consuming process. In nonvirtualized environments time is required to procure new hardware, and get it installed in the datacenter, install and patch an operating system and finally install and configure the required applications on the same and that can take a huge time duration to get going. This process also includes many other tasks to integrate the system into the infrastructure. For example, configuring databases, servers, firewall rules, enabling switch ports and provisioning storage. Below figure shows us a basic landscape of virtualization.



Benefits The benefits of using the virtual Box vis-a-vis Physical box can be summed up in the following chart.




In physical environments, the OS is installed on the top of the physical hardware and while upgrading ,we need to ensure that the device drivers are in right version and installed properly as per the requirements and latest compatibility matrix. If there are incompatibilities, there may be some adverse implications in terms of business cost ,time and personnel.

Virtualizing these systems save on this cost because virtual machines are 100 percent software. The virtual machine is a set of files. A virtual machine uses standardized virtual device drivers. The hardware can be upgraded without change to the virtual machine.

Architecture The difference between the Physical and the virtual architecture can be depicted in the below diagram:-


The graphics shown above illustrate the differences between a virtualized and a nonvirtualized host. In traditional architectures, the operating system interacts directly with the installed hardware. It schedules processes to run, allocates memory to applications, sends and receives data on network interfaces and reads from and writes to attached storage devices. In comparison, a virtualized host interacts with installed hardware through a thin layer of software called the virtualization layer or hypervisor. The hypervisor provides physical hardware resources dynamically to virtual machines as needed to support the operation of the virtual machines. The hypervisor allows virtual machines to operate with a degree of independence from the underlying physical hardware. For example, a virtual machine can be moved from one physical host to another. Also, its virtual disks can be moved from one type of storage to another without affecting the functioning of the virtual machine.

Virtualization is the panacea for many problems that related to the CPU, memory, and networking and resources bottlenecks. Virtualization is a technology that decouples physical hardware from a computer operating system and allows us to consolidate and run multiple workloads as virtual machines on a single computer. In short ,a virtual machine is a computer that is created by software that enables us to use all the computer resources in a shared manner and enables us to run  like a physical computer which runs an operating system and applications. Each virtual machine contains its own virtual hardware, including a virtual CPU, memory, hard disk, and network interface card, which look like physical hardware to the operating systems and applications.


Scope for Virtualization


There are multiple benefits/scope for virtualization as shown below :-


  • CPU Virtualization
  • Memory Virtualization
  • Networking Virtualization
  • File System Virtualization
  • Server resources sharing or Virtualization


In the next blog I will discuss the architecture of vSphere and its allied features in greater detail. In the future blogs, I will try to take take a deep dive into the various aspects of virtualization with special reference to vSphere and oracle. Gradually I will highlight why Oracle should be used in  virtualized environment like vSphere which leverages the performance of Oracle Database and also reduces the TCO of the DB in terms of licensing costs.


Further Suggested Readings : Best Practices for Virtualizing Your Oracle Database – Datastores