Q. Does VMware ESX 3.5 require a 64-bit processor with hardware virtualization features?

A. Yes and no. VMWare ESX server can be installed on a system with an x86 processor. During the installation it will look like Redhat Linux is being installed, but this install actually becomes the service console that houses the firewall, Apache Tomcat, the SNMP agent and other services. This console is used to manage the virtual machines (VMs) that run on the VMware hypervisor.

The ESX 3.5 hypervisor is a 32-bit kernel and if you run ESX on an x86 processor, you can only run 32-bit guest OSs. In ESX 4.0, the hypervisor is a 64-bit kernel, so it will take more advantage of 64-bit processors.

ESX 3.5 doesn't currently take advantage of the hardware assist technologies (Ring -1) in the Intel and AMD processors when running 32-bit VMs. VMWare uses binary translation, which it has found gets better performance than the native hardware virtualization in processors.

If you want to run 64-bit VMs, you do need a 64-bit processor that supports the Intel VT or AMD-V. You should also know that ESX 3.5 doesn't use the virtual machine monitor that Intel VT and AMD-V provide, even when running 64-bit VMs.

Editor's note: The information in this FAQ was corrected.

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