What are VMotion and Dynamic Resource Scheduler (DRS) in VMware?

A. VMware's ESX software supports VMotion technology, which allows a running virtual machine (VM) to be moved between ESX servers without having to stop the virtual instance and without the VM missing a beat in terms of traffic.

DRS uses VMotion capabilities to allow multiple physical ESX servers to be grouped as one resource pool of memory and CPU. This allows virtual instances within a DRS cluster to be dynamically moved between the members of the DRS cluster to balance resource usage with no downtime to the virtual instances. The level of automation of the movement between servers depends on the automation level selected (which allows only suggestions for where to move virtual instances): Partially Automated moves virtual instances only at power-on time, and Fully Automated automatically moves virtual instances according selected threshold (based on the move's recommendation level).