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I have found different and opposite opinions on the internet:

is it really possible to repair bad sectors on a hard disk ? should I replace the hard disk or just repair it?

I would be glad to read about your opinions.

I have just run HD Tune Pro, and it says:

Current Pending Sector

Description: Number of unstable sectors: 47
Status: The drive has unstable sectors.

enter image description here

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migrated from serverfault.com Sep 29 '10 at 22:21

This question came from our site for system and network administrators.

    
It is possible to force a drive to remap bad sectors, this is one of the the basic premises behind SpinRite. Data may or may not be lost in the process. Once the maximum number of remaps occurs, the drive WILL lose data. –  kmarsh Sep 30 '10 at 14:13

7 Answers 7

up vote 0 down vote accepted

Most HDDs will automatically perform wear levelling to reduce bad sector issues.

It will cost more time and money to repair any bad sectors than it would cost you to buy a new HDD for around £50. Especially when you consider your "repaired" drive could go bad completely and lose all your data.

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1  
Yes, and if the user is now seeing bad sectors, this generally means that the drive's own internal bad sector mapping is maxed out, so '47 unstable sectors' is only the number you can see - there will be 'x' more that the drive dealt with before it could not cope any more. Replace. –  Linker3000 Sep 30 '10 at 12:47
3  
"Wear leveling" is a flash memory/SSD term. The term for spinning HDDs is "sector sparing." There's more sectors free than what the HD allows to be accessed. The extra ones are there as spares to swap out if an error is detected. This makes the drive slower as the drive must perform a seek to get to the spared sector and then back. There are a limited number of them, after that, your drive will report sectors as bad. –  ultrasawblade Mar 24 '11 at 21:34

what do you value most 50-100EUR/USD or your data?

backup often. and for primary storage anyway use something you have a little bit of trust. disk get broken - it's a question of when, not if. bad sectors are indication that end of life is soon.

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3  
+1, with the prices of hard drives these days, you can get a 500GB for under $75. Purchase/clone/discard –  Dan Sep 29 '10 at 20:36
    
thank you for your replies: i was indeed wondering what to do: buy a new hdd or fix it. its not a matter of money, its a matter of what to do in these cases. thanks –  DonGoogle Sep 29 '10 at 20:47
    
+1 Backup often and remember that hard drives are disposable consumables, not permanent. –  John Gardeniers Sep 29 '10 at 21:49

I have used Spinrite to save drives others have thrown out due to "bad sectors", they are still running today. Thanks for all the free drives guys.

I guess it comes down to the definition of "bad sector"

A sector can get marked as bad when it just cannot be read reliably anymore, spinrite fixes these issues, and they are far more common than actual bad sectors (as in damaged).

.

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do you think it really fixes the bad sectors on hdds? –  DonGoogle Sep 30 '10 at 13:13
    
Depends on your definition of "Bad"..Yes been doing it for years. –  Moab Sep 30 '10 at 22:53

It basically depends how bad is it. A single bad sector (confirmed by software like MHDD) is a warning, if it is reallocated after a write, the drive could work for many months. On the other hand if it has few bad sectors, the drive is shot, buy a new one.

You should monitor SMART data and run smart test at least weekly on any drive that has data you care about.

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It depends. When a SMART diagnostics tool like HD Tune Pro or smartctl tells you that there is a Current Pending Sector reallocation or an Offline Uncorrectable sector this might indicate a fixable sector.

To be clear, the data at that location on the disk is hosed. You're not getting it back. Sorry.

However if you use a tool to attempt to write to the faulty sector the drive one of two things might happen:

  • It will fail to write to the physical sector on the disk. The drive will then reallocate a spare sector from the drives small collection of spares. This is bad. Your drive will keep working for a while. As the people at Google found out when a drive start reallocating sectors it is not long for this world. This will show up as a non-zero Reallocated Sector Count SMART attribute value.

  • The write will succeed and subsequent reads will also succeed. Further examinations with a SMART diagnostic tool will show that the Current Pending Sector has decreased.

What's happened is that the drive will likely have experienced what the drive manufacturers refer to as a write splice. That is a sector which is incompletely written. These generally occur when power is removed from the drive when it is writing. Because the full sector hasn't been written correctly when the drive comes to read that sector it reports a read failure.

Some hard disk manufacturers diagnostic tools will fix up these write splices. For example Seagate's SeaTools for DOS (not the Windows version) will offer to fix drives after it completes a full long test. This avoid unnecessary RMAs for Seagate and may recover an otherwise healthy drive.

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Replace the drive. Seriously. Don't mess around with either your own or the customer's data.

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Yes you can repair it but it depends how bad it is.. I worked at service center and we repair different kind of PC, Laptop problems.. When we diagnose a particular PC or Laptop we are using a software called "hirens"

You can download it and make it bootable in your flash drive...

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Welcome to Super User! It would be useful if you could add how you accomplish this task with Hiren's Boot CD. Thanks! –  Valmiky Arquissandas Aug 21 at 6:21

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