Comments for Why, or how, do files become corrupt?

Comment from aeneas on 2011-11-13

2011-11-13T16:26:35Z

I never had a single problem with file corruptions up until 2000s or so. Lately it has become an everyday problem.

Yet the first and a major cause is bad technology, bad controllers, and bad programming on modern system platforms.

It is impossible -or, at least >>was The "system file" has gone missing because the system ordered/flagged it for deletion and it will get deleted during some later clean up process. Not because some disk cluster has suddenly become unreadable. Because a chkdsk would reveal that a cluster x in file xy is unreadable.

At least 70% of "files missing" and "files corrupted" are a result of programming flaws on the system. The file has become corrupted because: The system has written data in an occupied cluster arbitrarily. That's why.
Other 30% are of course caused by a bad hdd surface and anomalies.

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Comment from Yeppers on 2010-04-12

2010-04-12T15:23:02Z

Leo �

Hi. I now clearly see the wisdom of your backup strategy composed of DAILY incremental backups with a monthly full backup. As in one of your examples in the article, I had two Microsoft documents (Word and Excel) on my desktop that suddenly would not open. Fortunately, I had made 2 backups of each file, each saved on separate flash drives. Unfortunately, those 2 backups were also corrupted and would not open. My full backup on a portable hard disk did have a clean copy, but it was old.

My question: Those two files were the only corrupted files (I hope, at least) and they were last modified on the same day. A subsequent Check Disk scan indicated that the volume was �clean�. Is it still likely that a bad sector had been the cause of the corruption? Can the SpinRite software you mentioned help me to recovery my files?

Thanks�

Quite possibly, yes. (Of course I can't guarantee it, but SpinRite comes with a money-back guarantee.)

15-Apr-2010

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Comment from Pookey on 2010-02-09

2010-02-10T02:18:58Z

In reference to the people talking about Cosmic Rays causing damage; you are CORRECT. It is one reason why ECC memory has been developed. In the unlikely event that a Cosmic Ray hits a stick of RAM, it may flip some of the "1"s to "0"s and vice-versa. ECC Memory works sort of like RAID 5 so that a hash is created for each piece of memory to ensure that when it is used, it has not been corupted by radiation.

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Comment from Menagerie on 2010-02-09

2010-02-10T01:12:09Z

You may like this little story as an epilogue to the problems of system crashes.
MANY years ago I worked as an engineer for the 'worlds largest computer manufacturer'!? I was called in when our biggest system - based in Portsmouth - crashed at exactly 9 o'clock every morning.
We took the system apart and virtually rebuilt the hardware and software platform! With NO SOLUTION!
Then.... someone had a bright idea... The Royal Naval Radar testing station was in the hills about 2 miles away and above us and one of our managers phoned them to see if they were testing anything that might be causing problems!
30 minutes later a large group of Naval techniciams were secretly in meeting with our senior staff!
The outcome was that we encased our computer room in foil insulated shutters and the RNTS changed their testing to 2am-5am!! We had no problems after that!!
Draw your own conclusions?
Oh yes... it was NOT the hard drives that caused the failure but system boards! Nothing on the drives was ever found to be damaged.

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Comment from Me on 2010-02-09

2010-02-09T19:58:02Z

There's also the bathtub curve; basically, either the drive fails right away or lasts for years. Still, things can happen, such as dropping a laptop or a power surge or accidentally swiping it with an extra-strong magnet or dust getting through the filter and causing a head crash; and of course they sometimes fail for no obvious reason. However in general it goes by the bathtub curve.

Also, do redundant backups. If you only do one backup and that goes, you're doomed.

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Comment from Mick Ames on 2010-02-09

2010-02-09T17:16:25Z

I had a serious HDD crash a couple of years ago and had to buy a new one. However, I managed to recover most of my files off the corrupt disk by using Acronis Disk Director on a bootable floppy. This package got me out of a very deep hole! I am very impressed by this software and NO, I do not have any connection with the company that produces or markets it.

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Comment from Mick Ames on 2010-02-09

2010-02-09T17:12:16Z

One sure way to get corrupted magnetic media of any kind is to put it on or near the floor on an electric train, overground or underground. The motor under your feet generates a very powerful magnetic field and will corrupt the data on the media. If you're carrying your laptop on a commuter train, keep it high off the floor. It happened to me a long time ago with a box full of floppies which were wiped clean on the London underground!

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Comment from Pat Van Dusseldorp on 2010-02-09

2010-02-09T17:04:54Z

Toyota problems with highly computerized, wireless devices, voice activated automobiles of today??

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Comment from Yee on 2010-01-08

2010-01-09T03:48:50Z

I always come across quite a number of crc errors and data corrupted every 1 out of 5-6 files I downloaded. At first, I could unRAR those files, but the next time I tried to do that, the files turned corrupted, crc errors or checksum does not match when I made a checksum file. Mr. Leo, would you mind commenting on this issues. Is my hard disk drive starting to fail or is it very common now that datas can be easily corrupted in hard disk after being kept for a period of time? Is there a way to minimize such problem as it started driving me nuts.

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Comment from Henk on 2009-12-30

2009-12-30T20:24:36Z

Alpha, beta and gamma rays are everywhere around us. Part of these rays are coming out of the earth (e.g. alpha rays are emitted by the gas Radon which leaks from cracks in the shell of the earth) and another part is coming from outer space. Compare it to the light coming from the sun. Cosmic rays may contain high energetic neutrons, protons, electrons and so on. Some places on the earth are absolutely unfriendly to life and just as you may develop cancer after exposure to sunlight you may also develop cancer by breathing air with Radon in it.
As a scientist I do not suppose hard drives to fail by a normal exposure to the rays mentioned above--this story is probably an easy way out for someone who can not think of anything else. What about the rays used at airport security checks? They won't kill a HDD as far as I know.

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Comment from Lee Nelson Guptill on 2009-12-30

2009-12-30T16:44:08Z

Frank, how in the world would a person be exposed to gamma rays in normal, everyday circumstances?

By virtue of living on planet earth. Gamma radiation is one component of Cosmic Radiation ( http://en.wikipedia.org/wiki/Cosmic_ray ). Miniscule amounts, but there.

31-Dec-2009

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Comment from Bharat Bhardwaj on 2009-12-29

2009-12-30T06:29:39Z

well, I see, yet again, you emphasise the point of 'backup'. however, my question is, should one backup only the computer or laptop or even the online content such as, email IDs, social bookmarking profiles. & much more?

would my emails not be secure with a paid account with yahoo? should i sign up a contract with a third party site that claims to make a backup of all my online content? should i trust a site such as:

backupify.com

which is a recent entrent in the 'data backup' industry?

Your help would be really appreciated in the matter.

Thanks yet again for such a wonderful resource!

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Comment from Nicholas Gimbrone on 2009-12-29

2009-12-29T23:05:44Z

Correct powerloss can cause data loss. Windows may not have flushed all of a modified file's contents to disk even if you have done a "close" on the file (depending upon the details of how you opened the file). Thus, it is easy for a poorly timed powerloss to cause data you thought was hardened to disk to be lost. This problem should not exist for a shutdown, as the operating system knows to flush those buffers during that process. A good/professional programmer knows how to take steps to prevent such data losses (but most "programmers" are not good or professional in their profession ;-).

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Comment from Alan Hart on 2009-12-29

2009-12-29T20:02:39Z

It seems that a careless shutdown or accidental power loss can cause file damage...can you comment?

Same basic idea: sectors can fail to be written completely as the power disappears from the drive. Add to that the fact that the operating system may not have the opportunity to write all data to the disk and everything from incomplete files, to completely corrupted directories can result.

30-Dec-2009

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Comment from Frank Golden on 2009-12-29

2009-12-29T19:56:21Z

I believe that if gamma radiation (very high energy x-rays) can cause data coruption on a HDD you have a more serious problem. Your exposure to the same radiation.
As it is gamma should have no effect on a HDD.

Moving a drive while it is in use or dropping it can an most likely will cause problems as Leo suggested.

Again if you have a gamma source near enough that you think it could be causing your data corruption then you yourself are in some danger.

I've actually had a respected electrical engineer I know comment that "cosmic rays" (no idea if that's gamma or not) can, in fact cause problems. It's very rare, but the same cosmic rays that we simply live in by virtue of living on planet earth can, apparently and very rarely, interfere with the micro-electronics we now rely on every day. Just one bit "knocked out of place", so to speak, can be completely benign, or if it's the wrong one, cause a system crash. It's extremely rare as I understand it, so I wouldn't run around blaming all your system crashes on cosmic rays, I just thought it was fascinating because it's so counter-intuitive.

30-Dec-2009

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Comment from Gabe on 2009-12-29

2009-12-29T17:54:58Z

How can I be sure that my backup isn't copying corrupt files to begin with? Is that what the "verification" process handles?

It depends on the kind of corruption. If it's a physical problem, as outlined in this article, then reading the disk will show errors and is likely to return different data each time the bad sector is read - thus when the verification stage comes along the comparison it does fails. If the data is physically ok, but has been corrupted in some other way (some rogue program went in and turned all of your "a"'s into "b"'s) then the verification phase will simply verify that the corrupt data has been backed up properly.

30-Dec-2009

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Comment from Carolyn on 2009-12-29

2009-12-29T16:23:44Z

My son has an Acer 3000, and suddenly it won't power on at all. We have charged it for a long time, and tried it with and without the power cord, but it still won't come up. Can you recommend anything to try that won't cost anything? I am struggling right now financially. Do you know of any moonlighting jobs using your pc where you can work from home in the evenings or on the weekend?

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Comment from Dan Ullman on 2009-12-28

2009-12-28T23:40:19Z

Gamma rays cause these sorts of problems. A friend proved it to my by pointing out that hard drives are not protect from gramma rays. Seemed reasonable to me :). It was the only reasonable explain for the problem I was having... :)

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