When creating VMs with scheduler hints, scheduler hints will only take effect at deploying time. After the VM was deployed, scheduler hints will be lost.
Later on when someone try to migrate the VM, this VM can be migrated to a host which might violated the original scheduler hints. Same problems also exist for resize, cold migration etc.
A proposed solution was store scheduler hints so that it can be available for the whole life cycle of the VM instance, this can make sure the VM can retrieve and evaluate the scheduler hints before doing some VM operations so as to make sure the VM will always obey its scheduler hints during its life cycle.
A problem was where to store the scheduler hints, add a new filed in instances table or just store in system metadata (is metadata big enough to store large scheduler hints)?
