Data can be lost in many ways. The most common mishap is for you to accidentally delete one or more files you wanted to keep. This can happen to anyone in a distracted moment, through confusion, or because of bugs in the software you are using. The damage from this kind of error is normally confined to a small number of files, but it can be quite devastating when it occurs.
Less frequent but far more catastrophic are errors that damage the entire disk. Power surges or other power failures while the drive is in the middle of writing can cause this to happen. Normally only the file you were writing will be lost, but if the allocation tables or directories become corrupted, other files files in the same folder or partition may be lost as well. Worse still, the head may ``crash", ruining not just the data on the hard disk, but also the hard disk itself. The disk can be repaired or replaced, but the data is lost forever – unless you have used The Vault.
Data can be lost even when the computer is not turned on. A hard disk can be damaged by a hard bump and will almost certainly not survive a drop to the floor. Bits on the medium can sometimes randomly change, perhaps as a result cosmic radiation or strong magnetic fields.
Floppies too are vulnerable to many hazards. Even though they appear rugged, floppies have been ruined just by being placed next to a ringing telephone. Leaving them in the sun, spilling coffee on them or simply misplacing them can all lead to loss of data. The magnetic medium may also be substandard or worn.
Although some of these possibilities seem unlikely, they all have happened. The message is clear – if you want to be assured that your data is safe, you must have at least two copies of your data at all times. Moreover, at least one copy must always be in a safe environment, out of the machine. It follows that you need two sets of backup disks so that the one can be kept in a safe place while the second is being written.
Backing up may take extra time, but the insurance is well worth it. Like all insurance, you don't need it until a loss occurs, and then it is too late to start using The Vault.