Performing a hot add of virtual hardware to an existing virtual machine

One of the greatest benefits of virtualization is the ability to give a virtual machine a hardware upgrade without buying new hardware. Since each virtual machine only uses a portion of the host's available resources, you can reconfigure the virtual machine and add additional hardware. You can add a USB controller, a CD drive, additional hard disks, SCSI controllers, vCPUs, and RAM to the virtual machines that have already been configured.

In the past, adding CPU and RAM to a virtual machine was a task that had to be done while the VM was offline, but increasingly, guest operating systems are establishing support for hot add, which means that administrators can increase the RAM and number of CPUs of a virtual machine while the guest is running.

The most recent version of Windows and Linux support hot add vCPU and RAM. VMware publishes a Compatibility Guide page for Guest OS, which outlines features available for each version...