Usage scenarios

This is a set of ideas how crtools can be used

Container live migration

This is the use case from what the whole checkpoint/restore project appeared. Container is checkpointed, then the image is copied on another box, then restored. From the remote observer point of view the container is just frozen for a while.

Slow-boot services speed up

If some service starts up too long (it can perform complex state initialization for example) we can checkpoint it after it finishes starting up and on the 2nd and subsequent starts restore it from the image.

Reboot-less upgrade

When replacing a kernel on a box we can do it without stopping critical activity. Checkpoint it, then replace the kernel (e.g. using kexec) then restore services back. In a perfect world the applications memory shouldn't be put to disk image, but should rather be kept in RAM.

Networking load balancing

Not the whole project, but the TCP repair can be used to offload an app-level request handling on another box.