Since some time ago I’m clear about next question: ¿what advantages do you see to OS-virtualization (like OpenVz or VServer) solutions against Full-virtualizacion solutions like (KVM or Xen)? And, this is my official answer for this question:
- Performance. OS-virtualization have got a lower penalization than the other one with respect to the physical machine resources. In OS-virtualization this is certainly a low different against a real machine:
- We can make checkpoints before software updates. Very interesting to no missteps and ease basesystem upgrading.
- Simplicity. When we need isolate a particular software components, we can use a VZ (OS-virtualization) as same way that a chroot environment. For example, I need to run a particular software architecture that supports only 32-bit on a cocrete AMD64 server.
- You do not need a disk image on which to install the guest operating.
- No headaches about sizing/resizing images
- You can set disk quotas consumption if necessary
- You can access to files directly accesing to the instance VServer/OpenVZ from the base host. For example, backing up is only needed on the base host, not on virtual host. Another example, you could share directories as Debian’s packages pool among multiple virtual host reducing the disk consuption (like Solaris Non-Global Zones).
- If our environment is homogeneous, in OS point of view, and assuming we’re living in a world GNU/Linux like, really we do not need that our virtualization system is able to virtualize BSD, SystemV, Windows and others OS …
- Physical resources can be reserved by virtual machines, but also can be left as sharing. This is all virtual machines use the resources on demand.