Currently I'm using ESX (v3 and v4) to test a scripted OS (Windows 2003) and application install DVD. The DVD ISO (8GB) is mounted on a 1Gbps NFS datastore and the VMDK's (20GB) are on an SSD mounted via NFS over a 10Gbps link.
It still takes a lot longer than I'd really like for to run through a test iteration and I'm wondering if mounting the virtual disks and ISO on a RAM disk on the same server as the hypervisor is running on would be worth my while. I can dedicate a server to this VM and 32GB of RAM in the system should be adequate to do the trick I'd guess. (1GB hypervisor OS, 28GB RAM disk and 2GB for the VM is < the 32GB available to me)
Since hosting a RAM disk within ESX does not seem possible I'm open to trying KVM/Xen/Hyper-V. KVM would probably be my first choice of these three.
Anyone out there tried this? Bear in mind this is purely for a test run of the installer, the VM will be discarded as soon as the test is completed so I'm not worried about losing data from the remote possibility of a power failure.