I want to do such setting that all vms should be paused(instead of shutdown) when host server reboots suddenly. Visualization tec: win 2k8 r2 with hyper-v
When you say "reboots suddenly", do you mean:
The first two instances will lose the running state of any running VMs. In any case, a paused VM has nothing saved to disk and shutting the host machine down will require that the guest VMs are either saved or shut down beforehand.
In the case of a graceful shutdown and reboot, you can configure how the VMs behave on a per-machine basis. You can choose that they are saved, turned off, or that the OS is shut down. Likewise you can choose what they do when the host machine comes back up.