Storage at it's most fundamental level is a bucket, where you store useful stuff that you may or may not want again later. Of course what you put that stuff into can vary in design; it might not be a bucket but a box instead, or a sieve, or a safe, or the dog's basket because he never sleeps in the damned thing anyway. Likewise with disk based storage there are various methods to implement a storage subsystem design, all slightly different, all have their own way of doing things.

The number of times that someone has declared tape "dead" probably numbers in the thousands. Users that deploy disk consistently report that their success ratios for backups and restores climb to 95% or higher. Yet companies should still view disk's place in the backup process as a temporary resting place for data and not a permanent one.