To achieve a combined Recording Bandwidth of 300 Mbps, distributed Recording needs to be enabled and defined requiring 2 or more installed hard-drives. The Recording Bandwidth will be limited to 150 Mbps using a single hard drive
Please reference the user-manual for the XRN-3010 , page 38 of the manual is shown below.
To enable Distributed Recording and you will need 2 or more HDD's to make this happen.