You can associate a pool with a specific storage device. For example, you may want your full backups written to optical disk for off-site storage. You have two ways to ensure that data goes to one specific storage device:
Keep a labeled volume associated with the appropriate pool mounted on a specific storage device. When a backup requires a volume with the correct label, Backup will find the volume on that storage device which is the only one available. If the volume resides in an autochanger, Backup automatically mounts the volume when it is requested.
In the Pools resource, associate the pool with the device in the pool configuration attribute list. All data is written only to that device.