Guardian OS 4.4.x or lower does not support 2 TB hard drives. The 2TB HDD technology was not in production at the time of the release of this version of Guardian OS.
Guardian OS 5.x and above is needed in order to support 2TB HDD technology.
Note that hard drive upgrades for 110, 210, 410 and 500/600 Series SNAP products are not supported or optional. It is possible to upgrade HDD capacity in existing expansions - S50 Series