About Parallels Virtuozzo Containers: Parallels Virtuozzo Container is the para-virtualization technology. It means that it creates virtual environment by splitting your operating system resources without actually installing another operating system over the host-operating-system. So basically unlike other common virtualization solutions it does ask you to install another operating system on the host. It will let you create containers, which will use the same source of your host operating system and they will be ready in few seconds to couple of minutes depending upon the configuration (templates) you choose.
So basically if you apply security patch or service-pack to host operating system it will be applied to containers (virtual-node) also, while other programs won't be available to containers. Good thing is it's pretty fast, easy to setup and deal with. You can learn in few minutes but one should use it only if they are going use one operating system for all virtual-nodes. Meaning that all containers inside a physical-node will share same operating system. You can't setup Linux as guest over Windows Server 2003 and vice-versa. Basically it's not for setting up heterogeneous OSes on one physical node but it's for sharing resources seriously.
That's what I understood about it. I have been playing with VMWare Workstation, Microsoft VM and Virtualbox but yesterday I had a chance to play with Parallels Virtuozzo Container as I had to move some (4 of them) servers to new physical node. Physical machine/server was not physically accessible and was at distant remote place.
Problem: I had RDP access to physical node which has Windows Server 2003 installed on it. Everything went well during the setup but while I was changing IP-address of the last container I got some-error can't execute command or something like that I don't remember exactly. We restarted container and physical node both. Somehow I was able to change the IP finally but while setting up the Default Gateway under the Network Configuration it was not taking that. I tried restarting container, there was no error but when I chose to "Assign IP address manually" and set the Gateway, say Apply and Ok. But next time I go on that Property tab and see that blank.
Solution: After trying things back and forth for about an hour, called up my friend and colleague Garvish, he joined me in troubleshooting and got the hint that probably "hardware node's host name will be conflicting with some other node on the network". We confirmed that and changed the computer-name, rebooted the system and issue is fixed.
In the end: The only problem is this issue would not have taken couple of hours and would have been fixed in minutes if there was a proper detailed message. Not sure if it would have been fixed in recent patches. I was using Parallels 4.0.x. So the conclusion is leave good informative messages for your users sometimes with technical details, depending on the target audience.