I encountered few troubles to find the good configuration for a Virtual Machine on ESXiV4.1.0 where I wanted to install a Cisco Unity Connection 8.5.1.10000-26.
The Cisco sizing page indicates that a Hard Disk with 160GB should be enough for Unity Connection but with that the hardware detection before installation failed with the message :
“Products not supported on current hardware”
http://docwiki.cisco.com/wiki/Virtualization_for_Cisco_Unity_Connection#Version_8.5.28x.29
So after some digging, I tried to increase size of the hard disk to 200 GB and the detection has been successful for Unity Connection installation.
Below, the configuration of the Virtual Machine. With a disk of 200GB with thin provisionning.
