The Pacific Northwest (PNW), sometimes referred to as Cascadia, is a geographic region in western North America bounded by the Pacific Ocean to the west and (loosely) by the Cascade Mountain Range on the east.
Mean time between failures (MTBF) describes the expected time between two failures for a repairable system, while mean time to failure (MTTF) denotes the expected time to failure for a non-repairable system. the MTBF is the sum of the operational periods divided by the number of observed failures.
An MTBF of 700,000 hours equates to about 80 years, which is NOT how long you can expect the hard drive to last, but a rating based on a bunch of math that the manufacturer chose that can be misleading.