Helping people with computers... one answer at a time.

External hard drives are a great convenience, but they're often used in different ways. As a result, maintenance needs may also be different.

Should I treat my external drive (used for backups) just like I do my internal drive which is subject to regular maintenance tasks like Disk Cleanup, Defragging and so on?

As with so many things, "it depends".

Whether or not, or how, you need to maintain your external drive depends on exactly how you use it.

Understanding what each of those maintenance tasks really do should help you decide.


You mention that you're using your drive for backups, so this part may not apply to you. But then again, depending on what you mean by "backup", it might.

I don't even have to ask how you use the drive for this one, the test is simple: if your external drive died and was completely unrecoverable, would that be a disaster or an inconvenience? Would you lose things that you cared about?

If it'd be a disaster you know what that means: you should be backing up the contents of your external drive. Perhaps you'd get another external drive to backup to, perhaps you'd backup your external drive to your internal and vice versa (totally valid, as long as the data is in two places on two different hard drives), but you should be doing something.

"If all you do is run a backup program to your external drive, then the only thing you need to do in terms of cleanup is keep an eye on disk space."

Disk Cleanup

To be honest, I don't even run this on my primary drive, but then I'm also a little geekier than average and know what to clean up manually and when.

If all you do is run a backup program to your external drive, then the only thing you need to do in terms of cleanup is keep an eye on disk space. When the drive starts to get too full, you'll need to delete something. Exactly what depends on how long you want to keep your backups, and exactly how depends on the backup program you're using. But there's nothing that the disk clean up utility would do that would help.

If you use your external drive for other things disk cleanup may help, but in reality it's still going to be focused on items that more traditionally live on your primary or system hard drive. Even if you're doing things other than backup with your external drive you should probably still just keep an eye on the amount of free space on the drive and take appropriate action if it gets too full.


First, realize that defragmenting a drive is only a performance optimization. In other words the only reason to defragment is to increase (or maintain) the speed of your hard disk. Particularly with an external drive, the USB or Firewire interface will often be the real limiting factor on speed and defragmenting the disk will have little to no impact.

In my opinion defragmenting is really also only called for if the drive is "busy". By that I mean that lots of files are being created, deleted, written to, moved around and so on, every day. That's typically not what happens on a backup drive. They get written to infrequently (when the backups happen) and that's about it.

Fortunately with most defragmenting tools, Windows built-in tools included, you can tell whether or not defragmenting even stands a chance of being helpful by running the analysis that the tools offer. I'll bet that the majority of the time there's simply no need.

Physical Maintenance

Since external hard drives are in their own case and have their own ventilation systems, this one's easy to overlook: it's probably a good idea to vacuum the ventilation holes to suck up any dust or debris that may have accumulated. This doesn't have to happen very often, not even as often as your main system's box. But since you should be giving your PC a quick vacuum every so often, that's a fine time to do the same with your external drive.

Just remember to turn both off when you break out the vacuum.

Article C3267 - January 14, 2008 « »

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?

Carl R. Goodwin
January 18, 2008 6:32 PM

I have found that when I try to only defrag my USB external drive, Windows decides to defrag the main drive too. I select only the external USB drive to defrag, but after a little while, it stops spinning, and yet Windows says that it is still defragging. It's kind of annoying, because I write to that drive all day every day, and hardly ever write to the main drive, so therefore, have no need to defrag it. Windows!

January 18, 2008 8:35 PM

If it ever comes down to data recovery, then defragged files are much more likely to be recovered. Some products like PerfectDisk allow defragging without opimization.

Adrian Barrett
January 21, 2008 10:09 AM

I run a small free utility on my system called "IOBit smartdefrag" which runs automatically in the background and keeps my main drive up to speed. As Linux looks after it's own drives in it's own way as standard I though it was strange that Windows had nothing similar and the hard drives always degenerated the files and fragmentation.

I personally would have belived that todays massive hard drives wouldn't suffer so much clogging of its file system, but then all the tiny files for windows and many programs are on my C Drive after all...!

(I always double and triple check comments and independent reviews before using freeware

Check this out - >>

February 5, 2008 4:00 PM

I read that laptop external drives don't won't well with Vista. Is this true? Secondly, what external drives (desktop or laptop) do you recommend? I am trying to choose between the Western Digital My Book Edition 500GB ($129.99 at Costco or the Seagate Pro Agent 750GB ($199 at Costco). Please help.


Leo A. Notenboom
February 6, 2008 9:26 AM

Hash: SHA1

I've not heard that. I'd expect 'em to be fine on Vista, XP

As for brands ... that tends to change from year to year. I
have two Maxtors I'm quite happy with, and two Western
Digitals. The WDs are the first time I've had one fail
within a short time, though. It was recoverable (using
SpinRite), and the drive is still in use and appears solid.


Version: GnuPG v1.4.7 (MingW32)


Drew Phillips
July 6, 2008 5:02 PM

Nice article Leo. I am wondering about the comment "when it gets too full". Well, how is this determined? Exactly what is too full? And how will one be notified of this status? About 8 years ago, back when recordable CD drives were still around $450 or so and media was expensive, I did not have the means to back up a secondary storage drive that I had filled to around 80% capacity. It started having problems reading data, and crashed with no recovery option, unless I wanted to spend $1500 (a lot of greenbacks in those days). As it is now, I keep my secondary disk(s) at around 50% storage capacity, but this is a layman's approach. I have not been able to find any info on external or secondary disk storage recommended limits, so I thought I'd ask you you know what they are or what the generally accepted limits are?

July 8, 2008 3:57 PM

Hash: SHA1

Unfortunately what "too full" means depends *entirely* on
how you use the drive - there's no single answer. Could be
OK to be at exactly 100% capacity, could be bad to have if
only 50% empty.

How will you know? Something that attempts to use the drive
will fail because there's not enough room to do whatever it
wants to do. Perhaps you can't backup. Perhaps you can't
save a file. Perhaps defrag doesn't complete like you want
it to. Perhaps many other things.

Sorry there's really no better answer or reecommendation.


Version: GnuPG v1.4.7 (MingW32)


October 15, 2008 11:51 AM

I have a 500g Seagate. Last night i attempted to run a back up [i use Ghost] and it said my drive was full. So when i checked 'properties' indeed, it almost was. So i deleted A LOT of the older back-ups, ranging from 37-41gig each, and still, it said there wasn't enough room.

Again, i checked the properties, and the available volume had not changed. So, now i tried 'disk cleanup'. It emptied the recycle bin, i had no idea the ext. drive had one ... but now it's been working on deleting the 'compressed files' [again, i didnt know they were there] but it's been HOURS and not much change. [the progress bar on the clean up window is only at 1 bar after more than 3 hrs.]

Is this normal?

I've also attempted a 'defrag' but again, windows said there is not enough room to do so. [i'm running XP home]

It does seem some utilities do not work the same on an external drive.



December 13, 2009 7:17 PM

I regularly defragment my external Western Digital hard disk as I do daily synchronization and the files are constantly being moved and deleted as stated above from Leo.

I have a found a free open source application that defrags external hard disks with ease. Doing a defrag simultaneously as I am typing this actually.

Works fine in Windows XP and should work on anything, it's a very robust application.

Can download from over here:

Then click on

Just inzip and enjoy ;)

September 15, 2011 11:58 PM

You should never vacuum your PC unless you want to fry it.

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