How to recover job data when using ray service to restart the ray cluster

Hi guys. I am using ray services function with KubeRay. I hope to enjoy the high availability and zero downtime upgrade for Ray clusters. Here are my queustions:

  1. If some ray jobs still running while ray cluster began to upgrade, is it possible for these jobs to resume and continue executing?
  2. Using external Redis as the backend of gcs can make this happen or not ? Where can I learn more about using external storage backend of ray gcs?
  3. I heard some teams let the job driver run on the nodes other than the head node. How can i do that? And, is this can make resuming jobs possible?

I found some related document about question 2: Ray GCS Fault Tolerance - KubeRay Docs