One of the new features coming from VMware is High Availability with Fault Tolerance. Traditionally, High Availability has meant that if a physical piece of hardware a virtual machine is running on has a failure, the virtual machine will be *restarted* on a different physical host. This will cause down time (albeit a small amount of down time) for the end user. Fault Tolerance addresses this situation by providing a mechanism that will cause no downtime in the case of a hardware failure. The way Fault Tolerance achieves this is by running a secondary virtual machine in lockstep with a primary virtual machine on a different host. All instructions sent to the primary virtual machine are sent to the secondary virtual machine in real time. In fact, if you view both virtual machine consoles at the same time, you will see the secondary virtual machine console mirror everything going on on the primary virtual machine (for example, playing a movie on the primary VM shows up on the secondary VM). VMware has posted a video of this technology.

Check out the video here…

For more information about Fault Tolerance, check out VMware’s website.

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