While losing a single file by accidentally deleting it or overwriting it is (by far) the most common form of data loss, losing a whole drive usually has a much greater impact.  

Traditional hard disk drives (HDD’s) have platters that spin, and any moving part will wear out over time -- typically 3-5 years.    There are two caveats to this rule: 1) there are a variety of special case drives manufactured especially for long-term, low-traffic storage; constant writes (security cameras); and 24x7 operation (SAN/NAS) in addition to general use type drives -- 2) there is a pronounced tendency for drives to die in the first year that ramps up again after four years when mechanical wear accumulates.  A cloud storage provider gathered statistics for their data farm of 25,000 drives.  It’s also worth noting that while the moving parts in HDD’s are usually what dies on you first, I have seen the drive controller cards (when separate) or the controller modules integrated in the main system board (aka motherboard) fail as well.

This is where redundancy comes to the rescue.  There are a number of redundant configurations available, but the most common for small businesses are: 1) Fixed size mirrored drives and larger drive arrays and 2) Variable drive arrays which are slower, but allow you the option of future growth without creating a whole new storage array later.

Although redundant storage gives you a warm fuzzy sense of security, it doesn’t solve all your problems. Redundancy is not the same as a backup. Human error is more likely to threaten any single file than drive failure. Redundancy is also not the same as High Availability (HA). HA is outside the scope of most small businesses since it makes your computer system an order of magnitude more expensive and typically requires dedicated staff. Redundancy on the other hand can be affordable and requires no special training to use.

A note on Solid State Drives (SDD’s):  They use the same technology as the SD cards in your phones and cameras without moving parts but have a limit to the number of times each sector of the disk with wide differences in manufacturing and use, no one has yet come up with a reliable lifespan estimate.  They are much faster and considerably more expensive than spinning drives. Unfortunately, that means if you are looking for a performance boost by using them for your PC’s OS drive, as a cache drive for a Database or something like UnRaid, they will help, but they will also ‘wear-out’ faster since those purposes also subject the drives to disproportionately higher traffic.