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does defragging cause hdd wear?

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February 3, 2008 8:16:52 PM

I have read several times in forums that defragging too often causes excessive wear to the hdd. This doesn't seem right to me for the following reasons-

-when you defrag a drive that has been done recently, not as many files are moved - a slightly fragmented hdd takes much less time to defrag than a heavily fragmented drive. I would think that defragging a drive that is only done every six months would cause much wear each time than one that is done every month, up to six times as much.

- running a heavily fragmented hdd causes the seek heads to move around much more, therefore increasing wear

If both those assumptions are true, then it should cause less wear to defrag more often, not less. Of course I'm not talking about defragging hourly or daily, but I usually defrag after installing new appps or games, which can sometimes be quite often.

If I am off base here I would like to know it and why. I don't claim to be a hdd expert.I am only familiar with windows defrag tool, dont know if others would be different

On a related note, I once heard a self proclaimed expert say to never use chkdsk as it is very hard on the hdd. Anyone know if this is true?



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February 3, 2008 9:47:57 PM

I think to answer this question, you have to look at the various mechanisms that can cause a hard drive to fail.

1. High temperatures that result in lowered magnetic properties, to the point where the surface of the platter can't store bits reliably anymore.

2. Internal contamination that either abrades the heads, scratches the platter surface, or otherwise causes interference between the heads and the platter surfaces. The internal contamination can result from flaking of the platter magnetic surface, seal failure and entry of contaminants from outside, or some other broken piece inside the drive.

3. Motor failure, such that the platters won't spin or are unable to maintain the proper RPM.

4. Bearing failure, such that the platters won't spin.

5. Head crash, where the head and platter touch while the platter is rotating, resulting in head abrasion, platter scratch, and internal contamination.

6. Voice coil failure, such that the head arm can't move.

7. Electronics failure, resulting in inability to read/write through the head, inability to send current to the voice coil to move the head, or inability to control the spin motor.

8. Mechanical damage from dropping, etc. that cracks or breaks a platter, causes misalignment of the heads/head arm, binds the platters or head arm, etc.

9. Complete erasure of the platters, including the servo tracks, resulting in inability to position the heads.

Repeated and excessive reads/writes to the hard drives place stress on some of the components inside the hard drive. Mainly, continuous read/writes cause elevated temperatures due to the current that's constantly being send to the voice coil to move the heads. They also cause continuous mechanical stress cycles on the head arm. After several million cycles, you elevate the risk of metal fatigue cracking, but this generally requires that a preexisting flaw in the head arm existed during manufacturing.

Bearing wear from continuous operation is another concern, although the fluid dynamic bearings used in modern hard drives have so little wear under operation.

For the most part, I'd say that overall mechanical wear on the hard drive components will eventually cause it to fail at some point, but in all likelihood there will be some other event that occurs that causes the hard drive to fail long before these mechanical stresses have a chance to cause a failure.

A power surge that fries the electronics (or erases a critical piece of servo information), a large temperature cycle that destroys the magnetic properties of a few sectors, a manufacturing defect in the platters that causes flaking and internal contamination -- these are the real-world reasons that cause a hard drive to come to its demise, not excessive seeks.

I don't see anything wrong with running defrag on a regular basis, nor running chkdsk. (Exception: If your file system is really messed up and you can't access your files, there is a chance that chkdsk can cause more damage than it repairs. Most professional data recovery experts will tell you that chkdsk will generally make the job harder, not easier when it comes to data recovery).
February 3, 2008 10:00:52 PM

Heat is typically the #1 thing that causes mechanical things to fail.

If you're keeping it cool, it should last a long time provided it's a quality product. Alot of drives can fail just simply because of poor manufacturing processes or quality of parts / handling of it etc.

performing defrags / chkdsk isn't going to do anything that wasn't about to occur anyway. But they are probably blamed because any mechanical weakness will show up under stress and these procedures are a bit stressful... but it doesn't mean they should be blamed for the failure.

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a b G Storage
February 3, 2008 10:22:13 PM

I think a hard disk that gets defragged every month or so will actually get less wear and tear than one that is never defragged.

Edit: here's a silly example. Let's say you have a 100MB mp3 or wav file on disk and play it 100 times this year. If it's fragmented, the reading heads will do a lot of work 100 times, jumping from track to track like crazy. If you defragment, they work hard once and have less work to do the other 100 times. Plus, the access speed will improve a bit.
a b G Storage
February 3, 2008 10:22:19 PM

If a drive goes bad because of defraging it, it was on the verge of failure anyway. And regular defraging should actually make normal everyday use on the drive easier...if that makes any sense
Reminds of the people who say turning your air conditioner on in your car at highway speeds will ruin the compressor. (the thing cyles on and off every minute or two on it's own anyway no matter how fast you are driving, and some cars even cut the air compressor off on purpose under hard acceleration as not to rob power from the engine)
February 3, 2008 11:54:08 PM

Well, the actual question the poster asked is "Does a hard drive defragmented a lot actually wears out faster than one that isn't defragmented always?"

For me, yes, but not always. It's because even if a hard drive is only, say "10% fragmented" , the defrag application will relocate hard drive data more than once. This probably explains the claims that it will wear out the drive because the effort to defrag the drive will actually use more seek/data access time that loading that fragmented data, and it will need defragging in the near future again anyway.

So in my opinion, I would only suggest defragging if the HD is seriously fragmented, maybe about 40% or above.
February 8, 2008 1:53:45 AM

Well, there is a feature that S.M.A.R.T. can detect, and it is related to how many times you start a hard disk, with this I mean, how many times you start your computer, or if you have sleeping mode for your idle hard disk. With some free utilities to see S.M.A.R.T. status, you can know the status of this feature. I think the usual limit is 15000.

The fact here is that the top and bottom sides of the plates in the hard disk, make friction with the hardware, so the limit is this value 15000 (generally).
May 22, 2009 1:14:33 PM

if you don't defrag your hard drive but every few months it will cause a natural wear and tear on the HD. when files are placed on the HD they are split up into many bits and pieces. they are then placed in various spots in the HD. and when you go to play or use those files. the HD has to locate all fragments from all over. making it work harder then it would have to if they are located closer. (example: if you have to walk a mile to pick pick up your clothes to take to the laundry mat. then walk 2 miles to get the soap. then 4 miles to the laundry mat. by the time it is all said and done your tired.) but if it is all side by side or a block away from each other there is less work to be done. so all in all it is better to defrag at least once a month to keep all files nice and neat. all depending on the usage of the HD. the more you install/uninstall or download the better it is to defrag. if you keep you house nice and neat the easier it is to find things VS living like a pack rat!
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