My previous experience with a large virtual “enterprise” environment was with VMWare’s ESXi and vSphere.
Performance wise, I was always fairly happy with ESXi knowing that it was a virtual machine of course. There were a few issues I recall:
silent data corruption (fsck’ing Linux and FreeBSD volumes would reveal inconsistent filesystem information, but there were never any errors reported to the VM) Live migrations were not always stable. In fact, most of the time it would result in an unexpected shutdown I doubt it was solely VMWares fault, as it could have been a series of mis-configurations and poor implementation descisions. Read More...