Why not just create the new devices and then stage the data from the old devices to the new? If the device is empty, there should be no need to complicate things this way? Ofcourse, if you have marked the old device on a pool, that will cause problems. If you have a lot of pools, using nsradmin is the easiest way to check this. Inside the nsradmin prompt, you
could use this to determine what pools use what devices.
If the devices field is empty, the pools can use all available devices.
nsradmin> show name;devices
nsradmin> print type:NSR pool