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Failing hard drive, how to tell which files might be corrupt

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August 26, 2006 6:36:21 PM

I have a Seagate 200 GB hard drive in my 2nd PC which was acting weird, event log showed multiple disc errors, and Seatools reported failing sectors.

The drive mainly contains movies, games and music and some ebooks, so none of it is part of my backup requimen.

So I need to offload all the files and then replace the drive under warranty.

Unfortunately I no very little about the error detection and correction involved in both the hard drive and the NTFS files system.

In the past I always recieved SMART warnings, or noticed odd noise, heat, vibration and was able to RMA the drives before failure. This time the problem came upon me without advanced warning.

When I copy files from a damaged DVD I get an error message when a file has an uncorruptable error. The ones that don't yeild an error are 100% intact. But I dont' know what happens when you try to copy a file part of which is stored in a failing or bad sector.

Does anyone know or have a link to knowledge about the error detection and correction methods involved and what notifications one can expect if part of a file is corrupted?

Is if safe for me to assume that any file I can copy without warning is exactly the same as was when written to the hard drive?
August 28, 2006 2:28:17 PM

You could MD5 each file, but if the source is bad then you moving corrupt data from drive to drive.
a b G Storage
August 28, 2006 4:30:53 PM

I recomend using a free program like Unstoppable Coppier to transfer all your files to a new hdd. Depending on the amount of curruption, you may have lost the file/video, but there are force copy programs that will Guess what is missing to currect the error.


Let me know.
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August 29, 2006 3:16:41 AM

If you try to copy a file from a damaged portion of the hard drive the error gets detected and if it can't get corrected you get an error message.

So any file I can copy off the drive is 100% intact, the rest stop with an error message.

Unless I use recovery software which will go ahead and copy every the file errors and all.


http://www.pcguide.com/ref/hdd/geom/errorRead-c.html

Quote:
1. ECC Error Detection: The sector is read, and error detection is applied to check for any read errors. If there are no errors, the sector is passed on to the interface and the read is concluded successfully.
2. ECC Error Correction: The controller will attempt to correct the error using the ECC codes read for the sector. The data can be corrected very quickly using these codes, normally "on the fly" with no delay. If this is the case, the data is fixed and the read considered successful. Most drive manufacturers consider this occurrence common enough that it is not even considered a "real" read error. An error corrected at this level can be considered "automatically corrected".
3. Automatic Retry: The next step is usually to wait for the disk to spin around again, and retry the read. Sometimes the first error can be caused by a stray magnetic field, physical shock or other non-repeating problem, and the retry will work. If it doesn't, more retries may be done. Most controllers are programmed to retry the sector a certain number of times before giving up. An error corrected after a straight retry is often considered "recovered" or "corrected after retry".
4. Advanced Error Correction: Many drives will, on subsequent retries after the first, invoke more advanced error correction algorithms that are slower and more complex than the regular correction protocols, but have an increased chance of success. These errors are "recovered after multiple reads" or "recovered after advanced correction".
5. Failure: If the sector still cannot be read, the drive will signal a read error to the system. These are "real", unrecoverable read errors, the kind that result in a dreaded error message on the screen.
August 29, 2006 3:30:28 AM

Quote:
I recomend using a free program like Unstoppable Coppier to transfer all your files to a new hdd. Depending on the amount of curruption, you may have lost the file/video, but there are force copy programs that will Guess what is missing to currect the error.


Let me know.


Thanks,

Anything that is important gets backed up to a RAID 1 array on another PC. The only files I wish to recover from this drive are those that are 100% intact.

I am trying Unstoppable Copier 2.28 with it set set to auto skip all damaged files.

It crashed on my when I tried to copy the files via network, but when I mounted the failing drive via USB adapter it seems to be getting the job done.
a b G Storage
August 29, 2006 1:54:30 PM

No problem. Glad I could help.


So your just going to abandon all those hapless little files that are just a little bit inperfect? Your pure evil.
August 29, 2006 8:53:36 PM

Anything important gets automatically backed up with Dantz Retrospect 7.5. The OS gets backed up with True Image 9.

If I need to recover important files from a troubled drive I usually use GetDataBack For NTFS.

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Basically I am just recovering a lot of .avi's and mp3's along with some ebooks, and so I only want the files that can be read without errors.

The drive just started failing, so only 13 out of 2222 files from the first 99 GB read are corrupt.

--

Its a 200GB Segate about 4.5 years into its 5 year warranty. It saw nearly 24x7 operation in a 2nd PC used for p2p, which is very tough on a drive.

I am bit dissapointed that I didn't get any SMART warnings prior to failure, every Western Digital drive that failed on me had clear signs of failure that allowed me to RMA or retire them prior to actual data corruption.

Maybe I was just lucky. Then again my WD drives were retired to light duty after their 3 year warranties expired. Plus the WD were in a hard drive cage that was actively cooled by the cases two 80mm intake fans, which probably helped.

BTW Even though it would be easier to replace the file rather than recover them I going to go ahead and try SpinRite and see if it really can correct errors than the hard drives built in error detection and correction procedures cannot.
a b G Storage
August 29, 2006 9:05:44 PM

Many times Smart errors are not reported unless something has critticly failed and is generation smart errors every second. As for get data back, great program.
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