VMware : Java Glossary

Potentially one virtual copy of the OS could monitor another, checking it for corruption. It would make it much harder for viruses to hide by corrupting system code.

Originally the purpose of VMWare was to let you test new versions of the OS and software simultaneously with the production system without any danger of interference or to run several different OSes simultaneously. Now it is used for much wider array of benefits:

• Ability for an ISP (Internet Service Provider) to isolate his various customers in their own private VM where they cannot disturb other customers.
• ability to migrate virtual machine to a different physical machine if the original one is suspect, e.g. a failing power supply.
• More efficient sharing of physical resources such as disks, RAM (Random Access Memory), CPU (Central Processing Unit) cycles. In a traditional system, most of the physical resources site idle, but must be sized for peak load.
• Simpler operating systems that can use virtual device drivers that don’t go to all the work of emulating a physical device, e.g. ethernet card.
• In times of low load, migrate virtual machines to so that power can be turned off on some of the servers. Cost of AC (Alternating Current) power is becoming more and the critical cost.
• Use of virtual appliances — an app published as a customised version of an OS along with application software.