Helping people with computers... one answer at a time.
Periodically defragmenting a hard drive can significantly improve its performance. I'll review how often makes sense and when you shouldn't.
How many times in a week is it good to defragment and run my anti-virus? Mostly, I run both one to two times in a week.
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My most common answer is that it depends.
It depends on several things, including your machine, how you use it and how much you do. As it turns out, even the version of Windows plays a part.
I'll give you a few guidelines.
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An "Average" Suggestion
Knowing nothing else, if you run Windows XP or Windows Vista, then I recommend scheduling the defragmenter to run once a week on each drive. Schedule it to run at a time when the computer is likely to be on, of course.
How do I schedule Disk Defragmenter to run with the Windows Task Scheduler? will get you started.
You'll note that I explicitly left out Windows 7.
Windows 7 does exactly this by default.
If you open up the task scheduler in Windows 7, you'll find that there's already a weekly task to defragment the hard drives in your machine.
What if your machine isn't on when the scheduled time happens? "Run the task as soon as possible after a scheduled start is missed" is selected. And it also requires that the machine be idle for three minutes before starting so it won't necessarily interfere with your work.
For most Windows 7 owners, there's nothing more that needs to be done.
The Case for More Frequent Defragmenting
If you use your computer heavily, and I do mean heavily (creating and deleting lots of files every day, writing and erasing lots of data in various forms), then there might be a case for defragmenting more frequently.
Because defragmenting your hard drive is solely a performance tweak, this is something that you can test for yourself. A couple of days of normal usage after you defragment your hard drive, defragment it again and see if you notice a difference.
Or, just defrag nightly, as I did for years. It really doesn't harm anything.
The Case for NEVER Defragmenting
Never, ever defragment a solid state drive (SSD) or flash drive†. There are two reasons:
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It doesn't help. The performance gains achieved by defragmenting a hard drive are specifically associated with disks that use a moving magnetic head over a spinning magnetic media: in other words, a traditional hard drive. Sectors which are located completely electronically as they are with SSDs and flash drives don't slow down as files become fragmented and thus, don't speed up when you defrag.
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It shortens the life of the media. Flash memory wears out the more you write to it. How quickly depends on the quality of the memory, of course, but the fact remains that the more you write to SSDs and flash memory, the sooner that it'll fail. And defragging a disk writes a lot.
There's no reason to defrag these devices and every reason not to.
Defragging Files That Can't Be Defragged
Files like your paging file, hibernation file, and the system registry typically cannot be defragged by normal means because they're locked and in use by Windows itself.
First, it's OK to let that be. Windows caches so much of its file system in memory that speed impact is typically negligible.
Second, if you do feel the need to defragment these files, you needn't do it nearly as often as your regular files. Once or twice a year, maybe.
How? PageDefrag, a free tool from Microsoft. It works by scheduling the defrag operation to happen the next time that you reboot your system, before Windows is loaded.
It's probably worth doing once after you've used your system for a while or if you change the location of your paging file.
Or not at all. That's typically been my approach.
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† Because SSDs are actually made from flash memory, this is technically redundant. To avoid confusion, I'm mentioning them both as many people think of them as two different things.
Article C4762 - March 11, 2011 « »
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.
June 2, 2012 7:47 PM
I am a professional (I have been in this industry for 35 years) and I know for a fact that defragging has very little effect on improving performance on today's computers. I am writing this to try and get people to ignore this BAD information that seems to be floating around the Internet.
If you are experiencing performance issues it is most probably caused by one or more programs (processes) doing excessive disk accesses at the time when you try and initiate a process yourself, one or more processes hogging the CPU or a faulty hard disk. These are the three most common reasons and there are tools available to help in determining which of these is the issue.
Look at "Process Monitor" (from Microsoft, actually created by Mark Russinovich before he was employed by Microsoft), the builtin "Task Manager" for CPU utilization (or better still "Process Explorer" (also written by Mark) and "chkdsk /r" which comes as part of the operating system.
"Process Monitor" will show you disk accesses. "Process Explorer" will show you CPU Utilization and "chkdsk /r" will indicate if your hard disk is faulty (among other things).
Again, forget the defragging: It's not worth the time nor the effort and if your computer happens to crash or loose power at the time a defrag is occurring you may end up re-installing corrupt software.
03-Jun-2012
June 3, 2012 3:34 PM
I think you are placing a lot more emphasis on the need for defragging than it is worth (i.e., giving people the wrong impression). The reason I say this is that there are VERY few instances where defragging actually produces much difference.
Tests have been conducted at PC Mag indicating very little improvement. I believe one of your other commentors referenced this study. As well, and in my past 10 years of servicing computers (as this is what I have done for a living for that period) I have never yet seen a performance problem resolved by defragging.
Defragging used to be worth doing many years ago when computers were much slower, but now that we have much faster hard drives, etc the benefit is no longer noticeable.
November 6, 2012 9:57 AM
i use 'smart defrag' which defrags automatically when my computer is idle..i never have to think about it.
January 22, 2013 3:34 AM
I don't know about other people, but I recently had the wonderful experience of doing maintenance on a PC that hadn't been defragged, disk-cleaned, or otherwise maintained for YEARS. After clearing things out, the tiny hdd had over 50 gigs of fragmented files. Defragging it most CERTAINLY allowed it to run faster in this case, but I believe this is an extreme case.
In terms of speed-boost being negligible, I think that's up to a case-by-case basis. I'm a very, very "heavy" pc user (LOTS of very large files being added, moved about, and deleted in a day) and I can easily notice the difference. I defrag my newest computer after I've done any massive data stuff (at the end of the day, I get several gigs of fragmented files), and it runs like no one's business.
22-Jan-2013
February 9, 2013 8:14 AM
I concur.
I've been working with pc's since before there were pc (IBM clones? Eeeek). I've never noticed ANY difference in performance after defragging. I think the only reason I do it, if I do at all, is I understand the mechanics behind it and it does make sense. But I have never see any positive effects sitting at the keyboard. Disk access tests may say different. But seat of the pants? No. And it certainly won't fix a jacked up pc as some people think.
What is frustrating is that so many people believe that many of their pc "problems" can be fixed by defragging... Even application issues or pc oddities. They have heard that defragging will fix their problems. It's a bit frustrating as a repair person. If the pc is acting up, I wouldn’t be wasting my time defragging it to see if that helps.
I can say that that the last time "I felt" defragging was helpful is with the old 20, 30 "MB" older drives. These drivers were S.L.O.W. The less you could get them to hunt around the platter the better. But that was long ago and I can't verify it.
I will say it does allow the average user to "feel good" when they are done. If that's all that happens, well.. that's not so bad :)