On hard disks and backups

It’s an inescapable law of physics that anything which has moving parts will fail eventually.

So, it’s no surprise that the things which fail most often in computer hardware are the parts that move: hard disks and fans (which I will cover in a later post.)

Even if the mechanics of your hard disk are still OK, the data is stored as a series of magnetised pulses inside and it is vulnerable to strong magnets, heat, vibrations and other such risks. Problems occur regularly, and hard disks include several techniques to help them cope with minor data corruptions without you ever being bothered by them.

Sadly, though, some data corruptions are too severe and that’s when users start to see problems. That’s when we’re known to ask the question which strikes fear into the hearts of many people:

“When was your last backup?”

There’s no substitute for having a known good backup, but it’s one of the things people often neglect until its too late. Even amongst those whom make regular backups, there are several common mistakes made.

  • How often should you back up? The answer to this question comes from asking youself “How much can I afford to lose?” If you create 20 documents a day and you only back up weekly, are you OK with having to re-write 140 documents?
  • What do you need back up? Make sure you back up all the information you want to keep, but not necessarily everything – if you have your original software disks, do you need to back up the software, or just the documents you create? Are you more likely to want to do a fresh install of the latest version of the software?
  • What are you protecting against? If you’re worried about a virus damaging your data, make sure you keep more than one copy of your data in case you have backed up the virus too. If you’re concerned about fire or flood, then make sure you store the backups at a different physical location.
  • How do you back up? There are many different choices – USB hard disks, magnetic tape, DVDs. Each has advantages and disadvantages. Is there any software you need to restore the backups? If so, make sure you have a copy of that too.
  • What protection do you need? Your computer may be password protected: but what happens if your backups get lost or stolen?

These are just a few of the many things you need to consider about your backup strategy. And it never hurts to have someone else take a second look, to point out anything you might have overlooked.