The main scenario is live migration of containers. We have live migration feature in OpenVZ since 2005. But it was always in-kernel implementation of checkpoint

The main scenario is live migration of containers. We have live migration feature in OpenVZ since 2005. But it was always in-kernel implementation of checkpointing Linux processes (https://openvz.org/Checkpointing_internals https://openvz.org/Checkpointing_internals). Linux kernel developers won't accept our patches to vanilla and we decided to implement C/R in userspace. Others scenarios are here https://criu.org/Usage_scenarios https://criu.org/Usage_scenarios