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You can defrag your external drive either directly from Windows Explorer or from the command prompt.

I have an older 360 GB external 'My Book' drive that I've used quite a bit. I'd like to defrag it in Windows 7. When I open System Tools to do this, it only shows my system drives, C and D. It doesn't list my external as available to defrag. I know that it isn't critical to do this on externals but I have written and rewritten to it quite a bit over the years. Is there a way to evoke the defrag from the command prompt or another way possible way?

In this excerpt from Answercast #91 I show how defragging an external drive can be done directly from Windows Explorer.

Defrag my external drive

Absolutely. There are a couple of ways to approach this problem.

I'm going to start by assuming that the drive shows up in Windows Explorer. In other words, on the left-hand pane where the drives are listed, there's a separate entry for that external drive, probably with a different drive letter.

I'll use drive F: as my example. Over there on the left hand side, listed with your system drive and your DVD drive, is this external drive.

  • Right-click on that.

  • Click on Properties.

In the resulting dialog box, should be an item called Tools (or potentially even "Defrag" depending on your version of Windows). In there, under Tools, is the option to defrag that drive.

In other words, you don't have to use these System Tools or whatever it was you were going to. Just do it directly from Windows Explorer:

  • Right-click on the drive;

  • Right-click on Properties;

  • Then click on the Tools tab in the resulting dialog box,

  • And you should have the defrag tools ready for you right then and there.

Defrag from the command prompt

To answer your other question, "Can you do it in the command prompt?" Absolutely.

You may need to run your command prompt as administrator: that means right clicking on the command prompt icon and use"Run as administrator." Once you do so, the commands actually are fairly simple. Defrag, space, the drive letter (for example F), colon and return.

That's literally it:

  • Defrag F: (or whatever your drive letter happens to be) in the command prompt. That will run the command prompt version of the defragging tool.

Either way, yes, defragging external drives is a fine thing to do every once and awhile. It's not hugely important. It's not as important as defragging the drives that are installed in your system.

Typically any performance gains are pretty much overshadowed by the speed of the USB interface but certainly after many years of use, things could be pretty seriously fragmented and as a result, it wouldn't hurt to run a defrag on the external drive.

(Transcript lightly edited for readability.)

Article C6282 - January 28, 2013 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

January 30, 2013 11:21 AM

I think if the external hard drive contains system image(s) and/or backup files, they should not be defragged. Defragging could compress the files, rearrange them and make them unusable.

Defraggging will not compress, and would not make them unusable. Other than making disk access a tiny tad faster (which would, itself, probably be lost to the slower USB transfer speed anyway) defragging an external drive should be completely safe.

Mark Ogilvie
February 2, 2013 11:29 AM

In this case, it is an IDE hard drive. However, many external drives are now SSD (solid state drive), which accesses data differently and would not benefit from defragmentation, in fact, defragmenting a SSD drive (whether internal or external) would shorten the life of the drive.

February 2, 2013 3:32 PM

@Mark Ogilvie,
I've read a bunch of articles from Leo on that as well, so good point. Here's a good one:

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