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If External Hard Drives Can Fail, Should I Bother with One?

I’ve been told that an external hard drive can still be corrupted after you transfer files, pictures, whatever. Should I still purchase an external hard drive or get a subscription to a good online service?

Yes, yes, a thousand times yes.

Everything can fail, including the online service. Backing up isn’t as much about which backup technology you choose as it is about having multiple copies.

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The Golden Rule

The golden rule of backups is this:

If there’s only one copy, it’s not backed up.

When you have data backed up (meaning you have made multiple copies, in any medium) then data loss will only happen if all of these copies are destroyed at the same time.


You’re quite correct in that there are things that can go wrong with external drives. They are hard drives, after all. They can and probably will fail eventually. But if you still have your original files, you just replace the external hard drive and resume backing up.

Online services can fail too. Your account could get hacked; your data could be destroyed. The service could suffer a failure of some sort, or even go out of business. But again, you still have your originals and thus you move to a different backing up service and resume backing up.

When it comes to backups, it’s a numbers game. And more is always better. However, if I could get everyone to just back up to an external hard drive, 99% of the disasters that I hear about would stop happening.

The rule of three

The Rule of Three

So what about that 1%? Well, one rule of thumb is to have:

  • three copies
  • on (at least) two different media types
  • with one stored elsewhere

That reduces the probability of disaster even more.

For example, if you add an online backup service for your data, in addition to backing up your entire machine to an external hard drive; then your data is protected from things that could take out both the computer and the external hard drive, like fire or theft.

I personally would not use an online backup as a replacement for backing up to a hard drive. But I do see it (and in fact I use it myself) as an additional part of an overall backup strategy to further reduce the possibility of disastrous data loss.

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6 comments on “If External Hard Drives Can Fail, Should I Bother with One?”

  1. Hi Leo,

    You wouldn’t believe how many friends I have who tell me that one backup is enough. Oh how wrong they are. I constantly tell them (like you did): if you just have one copy, it’s just not a backup. I don’t know how many times I’ve recommended off-site backup to my people but the majority just wouldn’t listen and then come back to me later whining: PLEASE CAN YOU RESCUE MY DATA??? :) Well, here is an article of why a backup of a backup is always a good choice:

    • To be clear, one backup is a backup. As long as it is a copy of the data. What I see are people moving data to their backup drive, thinking that’s a backup after they delete the original copy on their machine. They’re left with one copy, and only one copy – regardless of where you put it – is not a backup.

  2. I recently had a three year old hard drive in my computer. Suddenly, a blue screen of death popped up and that was the end of the drive. Not even the freezer method or several attempts in a USB hard drive enclosure would get the thing to work. Other drives in the enclosure did work, suggesting it was most likely the drive and not the enclosure.

  3. For data that have special importance, the integrity can be further enhanced by creating redundancy using QuickPar. (On each of your three or more copies of the data of course.)

    When storing on CD/DVD for a long period, best use a rewritable disk, not a single use disk, as the rewrite storage technology is different and less susceptible to bit rot.


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