I'm running into an odd issue that I have not found any information on. I'm running ESXi 5.1 Update 3, fully patched. Two Server 2012r2 virtual machine instances, fully patched, VMWare Tools installed.
Here is the issue: when I have the VMWare Tools virtual CD attached to the VM, everything works as expected. When I "eject" the installer or when the VM reboots, it slows to a dead halt. The VM uses, at most, 28-32 MHz of CPU, even though it has 4 vCPU provisioned. Ping times go in a pattern of Timeout > latency greater than 1000ms > latency at 1ms > Timeout.
I can then open the console in vSphere, click VM > Guest > Install/Upgrade VMWare Tools > choose Interactive so that the installer attached again, and the VM's instantly snap back to normal. Responsive, stable ping, CPU usage as expected.
Anyone ever seen something like this before? I'm at a loss to even start troubleshooting.
I know it seems to be somehow related to mounting an ISO image. But on a side note, what is the NIC type you're using? If it's E1000, change to VMXNET3. It may potentially help.