Offered in capacities up to 20TB, the Exos X20 is Seagate’s (and the industry's) highest-capacity 3.5-inch enterprise hard drive. This CMR-based drive is targeted at cloud datacenters where it directly competes with the Western Digital Ultrastar DC HC560. We found lots to like about the Exos X20, including helium sealing, a 2.5M-hour MTBF, and a five-year warranty.