This is a short how to on using a USB drive to backup your NAS shares. The only thing missing is the Snapshot but when setting up your task it will ask you to create a snapshot.

http://kb.open-e.com/entry/112/

Configure your Volume group and dynamic unit (an 8TB thumb drive)
We created our NAS volume and assigned a snapshot to it

In configuration ->NAS settings we enabled local backup settings
CONFIGURATION -> NAS settings -> Function: Local backup settings.
We selected Dynamic Volume and created a backup device
MAINTENANCE -> backup -> Function: Create new virtual backup device
Create a new backup tape, I named this USB
MAINTENANCE -> backup -> [device_name] -> Function: Backup device tapes.

Create a backup pool named backup
MAINTENANCE -> backup -> Function: Create new pool
We created a backup task named test1 and will backup share test and backup_db_lv0000
MAINTENANCE -> backup -> Backup tasks -> Function: Create new backup task.

We can start the backup task manually, by clicking on the green play button
MAINTENANCE -> backup -> Backup tasks -> Function: Create new backup task.

Or we can create a backup interval of once every 10 minutes
MAINTENANCE -> backup -> Backup tasks -> [task_name] -> Function: Create new schedule for backup task.

We have 2 backups
STATUS -> tasks -> Tasks -> [Task_type] -> Function: Tasks log.