Tenant device states

In some circumstances, probably after a restore, serviced switches tenant devices but is unable to remove the previous device from the NFS export mount. When serviced is in this state, the master host and the delegates are using different devices, and the two devices quickly get out of sync.

To prevent errors, serviced does not start services when the tenant mount and export mount are backed by different devices, and the services are assigned to a resource pool that has DFS access permissions. When tenant mount and export mount are backed by different devices, and services are assigned to a resource pool that does not have DFS access permissions, or when the tenant mount and export mount are backed by the same device, serviced does start services.