The nature and design of OpenVZ Containers entails a limitation in that it's not a good format for file-servers, such as Amahi.
You will need to use a KVM host. OpenVZ containers can only have one volume of space assigned at any one time and managing them any way aside from command-line becomes cumbersome.
Adding host drives directly to a VM in Proxmox involves understanding the structure of the folders that Proxmox uses, as well as the command line for QEMU. Proxmox recently updated all the way to version 3.0 RC2 (at time of post) and I will indeed be testing when Amahi7 is released... however I am possibly veering away from using greyhole with what I need my hypervisor machine to do.
A sample of the drive adding command....
- vm101 is the ID of the virtual machine you want to point the drive to
- sata01 identifies the drive once mounted and the protocol for it
- /dev/sdb is the installed
but not mounted drive in the proxmox machine.
Once you boot the KVM you add this drive by manually, permanently mounting it to the VM.
..from experience I've found..
Greyhole is definitely handy if you have Amahi running in a tower that exclusively runs Fedora where you may have many many different sized drives, but in a virtualized environment, using Greyhole adds a lot of un-necessary overhead and I/O, and too much I/O on a drive or LVM group will bog down a hypervisor that isn't using iSCSI for the drive volumes. And using drive images instead would introduce yet another layer of overhead that you don't want, slowing down your file-server and hypervisor.
In many cases, I would suggest that if you're savvy enough, just run Fedora 18 and Amahi 7 in a very robust machine and run Virtualbox or RHEV/libvirt to get virtual machine at the same time.
Oh and to address an earlier post... install with only the OS and LZ drives in the VM, and add greyhole disks only AFTER installation.
Correction: you CAN have live data in the drives you add, but you will need much time to allow for greyhole to re-index and you must have your dashboard match absolutely as it was before.