Virtualization is a concept in information technology that combines an organization’s IT resources, such as networks, processors and storage, into pools from which the dynamic allocation of the resources is possible. It has the overall effect of improving utilization of IT resources. The use of system virtualization helps to create several virtual systems using one physical system. Implementation of system virtualization is possible using Hypervisor technology. A hypervisor refers to software with the capabilities of virtualizing system resources.
Type 1 and Type 2 virtualizations are the two main forms hardware virtualizations approaches normally used in IT. In type 1 virtualization, the Hypervisor installs directly on the physical server hardware. No other operating system needs to be present to support the Hypervisor. For type 2 virtualization, however, the base operating system, such as Windows Server or Linux, has to exist on which the Hypervisor installs. The base operating system manages the operating system services since it has a direct access to the server’s hardware. Another is that type 1 hypervisors are usually faster and more secure than type 2 hypervisors. Type 2 virtualization, however, has a smoother configuration process, unlike type 1 virtualization. The similarity between the two types of virtualization is that the virtual machines are completely oblivious of the type of virtualizations in place. They only intermingle with the Hypervisor. For both, there is also a physical system present that supports the virtual systems.
Using VMware in a windows server network scenario would be more viable when implemented with type 2 virtualization as opposed to type virtualization. The reason is that; VMware best operates on another operating system, in this case, Windows Server. More so, there is no restriction in the number of supported laptops and desktops.
Virtual Disk Formats and Applicable Environments
In dynamically increasing virtual disk storage, the initial space created is usually small since there is not much data involved. As the requirements for the virtual machines continue to increase, the size expands proportionately to meet such demand. In the end, the size expands to the maximum limit set for the virtual disk. In a business setting, for example, an administrator might configure virtual storage with a capacity of 100 Gigabytes. If only 25 Gigabytes is in use, the physical disk will have the capability to hold 75Gigabytes more should the need for more storage arise. In the meantime, only 25 Gigabytes will be in use.
Expanding disk storage is most useful when performance is not a priority like in test server environments. Its main advantage is the flexibility of part provisioning of a virtual machine’s storage rather than the full storage provisioning. The snag, however, is that there could be the unexpected overloading of the host if there is no proper planning in a production environment.
In a fixed size virtual storage, the allocation of space is done in full. The advantages of such type of memory allocation are predictability and stability. With a fixed size disk, one is assured of enough space available. In the events of power failure, fixed disks are always stable, unlike the expanding storage disk storage methods. On the contrary, such disks may have idle capacity storage hence under-utilization.
A differencing disk comes in handy when some changes in a virtual machine may require rolling back before implementing the changes. The differencing disk logs all changes made leaving the original disk intact. A good network application for a differencing disk is a lab environment scenario because differencing disks have very slow speeds. A lab network may also have a requirement for rolling back changes before implementing them.
