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Repairing Bad Sectors


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#1 purple frog

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Posted 30 September 2007 - 03:55 PM

Hi, Sorry if there is a thread on this, but the 4 letter limit on the search prevents the word bad, and it would be impossible to scroll through each page so here is my problem.

I have a western digital 160 gb HDD, in a Dynex aluminum case, and it has worked great for my storage needs until recently. my computer locked up on me a while back, no blue screen just totally unresponsive. i ran different diagnostics and checked the event log, and found it was possbily related to bad sectors.

I ran HD tune, and it found 6 bad sectors on my external drive.

Is there any way to repair these sectors?

If not is there a way to section them off separately so my computer wont try saving there and lock up again?

thanks ahead of time for your help.


my system info:

XP SP2, 1GB ram, with 2.7 ghz processor.

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#2 DaChew

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Posted 30 September 2007 - 05:08 PM

drives that develope bad sectors are often failing, sometimes it's just a power glitch

it's best to try to return them to factory state with the diagnostics from the manufacturer and a slow format

bottom line is, back up(however) any data on them as soon as possible

fat32 seems more susceptible to this than ntsc
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#3 Platypus

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Posted 30 September 2007 - 07:34 PM

Is there any way to repair these sectors?

No, unless they have been incorrectly identified as faulty. Considering how tiny a space loss 6 faulty locations is, it's not worth trying to recover them.

If not is there a way to section them off separately so my computer wont try saving there and lock up again?

Yes, you can run chkdsk from the command prompt.

chkdsk /r locates bad sectors and attempts to recover as much data as possible to repair the file using an alternative location. Each faulty sector will prevent the use of however many adjacent sectors are allocated as a disk cluster (the smallest allocation unit). The default NTFS allocation unit is 8 sectors, so the data from 8 sectors will have to be relocated for each sector that is marked bad & the associated cluster will then be left unused. The data from the bad sector may be unrecoverable, so the file may still be corrupted.

chkdsk /f finds & fixes a range of potential faults with the file system

http://www.microsoft.com/resources/documen...k.mspx?mfr=true

However, as DaChew has pointed out, appearance of bad sectors may well indicate the drive is starting to fail. Modern hard drives have self-diagnostics that operate "behind the scenes" to map out sectors it recognises are becoming faulty to a reserve of spare sectors that the drive comes with ex-factory. That's why you don't get any bad sectors on new drives these days, any that do exist have already been mapped out and substituted by some of the spares. If bad sectors are no longer being transparently replaced by the drive self-diagnostics, that would indicate it has run out of spares. So any further bad sectors will start to corrupt files and need repeated running of chkdsk to try to recover.

How long was the warranty on the drive?

Edited by Platypus, 30 September 2007 - 07:37 PM.

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#4 purple frog

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Posted 30 September 2007 - 09:35 PM

im not sure about the warranty of the drive, it was one from wal mart (i know, dont shop there, but i had a gift card) and it was purchased about late January of this year; so any 90 day warranty will be gone.

on edit: I checked the wd site, and found that the western digital Caviar (the brand i have) comes with a 3 year warranty; now the question is how do i prove the purchase date for my hard drive?

Edited by purple frog, 30 September 2007 - 09:42 PM.


#5 oldf@rt

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Posted 30 September 2007 - 09:46 PM

The standard warranty for western digital external should warranty the drive from date of manufacture if you have no proof of purchase http://support.wdc.com/warranty/policy.asp If you can find your receipt, you will be warrantied from the date of purchase.

I will note that every hard drive that I have worked on has some bad sectors, what you need to be concerned with is increasing bad sector counts. That is a sign of hard drive failure beginning. Example you have six bad, you run check disk again, and have 14 bad, you get worried, run it again and have 31 bad now, if you keep just getting six, you should be ok. Just make sure that you have a back up of your important data. Hard drive failures only seem to occur when you have no backup.

Edit Warranty Information.

Edited by oldf@rt, 30 September 2007 - 09:50 PM.

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#6 purple frog

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Posted 01 October 2007 - 12:45 AM

this drive was originally an internal, i bought it and put it into an enclosure. and this drive is my backup/ media drive bc the one ing my computer is only 40 gb. but thanks for all the help, ill keep an eye on the bad sectors. also, any tips to keep my computer from locking up bc it tries to write to those bad sectors or is the chkdsk /r the best option?

#7 oldf@rt

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Posted 04 October 2007 - 01:21 AM

If you are only using the external hard drive on windows NT, 2000, XP, or vista, make sure the drive has been formatted using the NTFS file system. If the file system is ntfs, windows should not attempt to write to the bad sectors.

The command should be chkdsk X: /V /R /X The first letter X is the mounted volume letter.
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#8 komski

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Posted 04 October 2007 - 09:41 AM

The idea of being able to mark a cluster as being bad is not new. The FAT file systems also support marking bad clusters. The difference is that cluster marking and remapping in NTFS is "almost" automatic. Marking bad clusters within a FAT file system requires a disk utility, such as CHKDSK. Even under NTFS, cluster remapping is only likely to be successful if the bad cluster is detected on a write operation. If the bad cluster is detected on a read operation then it is probably an unreadable sector and so remapping would be ineffective.

All drives develop bad clusters and during the original format these are mapped in a hidden area of the drive. SMART enabled drives can continue to fill this area until it fills up and then such mapping cannot be continued - this is the point at which most file-system corruption begins. Reformatting does not re-zero this hidden area though a zero-fill of the drive can sometimes cause the whole drive to be remapped from square one. A zero fill is the nearest equivalent to a low-level format and is what I would suggest if you intend continuing to use the drive. Personally I would only use a drive that is developing new bad sectors for testing purposes or as a paper-weight. Others have used such drives for a long time but with the cost of storage at an all time low I don't see the point.

#9 DaChew

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Posted 04 October 2007 - 10:32 AM

:thumbsup:

good post, I was under the impression the zero fill from the manufacturer and then a slow format ntfs was the best way to make sure bad sectors got remapped correctly? If bad sectors keep showing up after that then the drive is on it's way out?
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#10 purple frog

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Posted 06 October 2007 - 10:44 PM

actually, no more bad sectors have appeared as of yet, its still holding at the 6 i first noted here. the drive is NTFS format btw. would these bad sectors cause a "disk io error" in large file transfers that cause the transfer to be aborted?

#11 Platypus

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Posted 07 October 2007 - 08:58 AM

Yes, if any of the bad sectors formed part of a file you were trying to copy, they could be responsible for a disk I/O error.

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