Well, this is what I was referring to with the HA features of vSphere. It works basically like a compute level RAID. The VMs were stored on a SAN and vSphere monitored each of the compute blades. If one went down, the VMs were seamlessly migrated to a hot spare blade. The vSphere docs claim this can be achieved with zero packet loss -- a claim I was never able to test or verify. If you're worried about losing multiple machines, just add multiple hot spares.
Of course, this doesn't help if you lose an entire rack or the data center. I concede this was a trade-off. But given how many times an entire region went down when I was on EC2, I was satisfied with the risk based on the colo environment's uptime record. The provider did offer another facility, but the latency between the two was too high to be of practical use in a failover without keeping a completely mirrored configuration in both locations.
It sounds like you have some experience with vSphere, so I don't intend to be patronizing. But there's a huge difference between "enterprise" virtualization and what you get with an ad hoc setup using desktop virtualization tools.
Of course, this doesn't help if you lose an entire rack or the data center. I concede this was a trade-off. But given how many times an entire region went down when I was on EC2, I was satisfied with the risk based on the colo environment's uptime record. The provider did offer another facility, but the latency between the two was too high to be of practical use in a failover without keeping a completely mirrored configuration in both locations.
It sounds like you have some experience with vSphere, so I don't intend to be patronizing. But there's a huge difference between "enterprise" virtualization and what you get with an ad hoc setup using desktop virtualization tools.