Implementation - Initialization
Authentication, authorization and access control are handled by XenoServer.
The migration client forks, creating a listener process that signals the block-driver to enter record mode.
In record mode, the driver copies the writes to the listener process, which transfers them to the destination.
The other half of the migration client begins the bulk transfer.
At the destination, there is also a fork in the daemon. One receives the bulk transfer, the other receives the deltas.