1. Utilizing server resources at fullest (by installing virtual machines side by side)
If a physical server has 100% resources for example, in the normal architecture at the peek time also the operating system is able to utilize its resources between 25%-50%. In that case, we are wasting the other 50%-75% resources. But with the use of virtualization using a Hypervisor we are creating more than virtual machines. They all are running side by side, they have their own allocated resources. So if you assume like, we have created 2 virtual machines(one windows & one linux) with 50-50 resources allocated for them, and in this case, we are utilizing 100% resources of the server.
2. Access to multiple operating systems simultaneously
3. We are using one physical server, to host one or more virtual machines (depending on the physical server resources). With this we are saving power, data center space and administrative personnel.
4. With the advantage of the features provided by vmware (vmotion, ha, drs, dpm) , we can get uptime of a operating system / application up to 99% .
5. As the virtual machine is made with a set of files, we can move it / copy it / back up it/ restore it very easily. So the administration of machine when compared to physical is very very less.
Also read this article VMware – Virtual Networking
Besides VMware, there are lot of virtualization products available in the industry. Everyone has their own feature set and specialties. Microsoft Hyper-V and Citrix Xenserver are the other leading virtualization technologies in the industry.