InstanceMigration


 * Launchpad Entry: NovaSpec:migration
 * Created: 2010-09-01
 * Contributors: JesseAndrews

Summary
Develop a feature to allow cloud administrators to perform maintenance tasks of physical servers. This feature will allow admins to shutdown an instance and move it to a new host node.

Release Note
An internal admin tool to move instances from a compute node has been added to OpenStack compute.

Rationale
Hardware fails. A user's instance shouldn't be permanently lost when hardware must be removed from the pool.

User stories
A member of the operations team notices that the hardware on a server is failing. To protect the users, the instances are migrated and the system is sent to the datacenter team.

Assumptions

 * more than one node exists
 * compute nodes are able to rsync/scp between each other (server setup should be limited ssh between nodes to only rsync) -- or the image is moved to the object store.

Implementation
a nova-manage command will be added that:


 * shutdown the instance
 * determines a new server to migrate the instance (via the scheduler)
 * the compute node that receives the run command retrieves the image from the existing server.
 * the network configuration is kept the same, and the new VM is restarted

Optimization:


 * when you take a snapshot, it creates a base and a delta (cow) file
 * the base snapshot could be copied before the instance is shutdown, then the delta (cow) could be moved after shutdown - which would be much smaller and faster.
 * potentially pause VM instead of shutdown