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I have a hard disk which has some bad sectors on it. And it said when I booted in Linux mint that I already need to replace the hard disk. But I don't have yet the money. I'm just a student. How do I do a low level format? What do I need to do before trying to do it?Is there a particular time span until all of the hard disk breaks down and lose all of my data wen it has already bad sectors on it? How long will a low-level format take, for a laptop with 2Ghz core 2 duo processor and 2Gb ram.

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If you want to know how long it takes, we'll need drive specs, not computer specs. –  BloodPhilia Sep 30 '10 at 16:03
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The terminology "Low Level Format" as used by MHDD32 and everyone here is incorrect. MHDD32 uses this term to refer to issuing an "erase" command to every sector on the hard drive. This is NOT what a true "Low Level Format" is. Writing to every sector will force the drive's firmware to indeed "recalculate ECC" and also remap bad sectors into spare sectors (if it has any left) - so this is useful for repairing drives with bad sectors (although the disk should really be replaced soon).

A low-level format is a process where the drive writes things like sync marks and sector markers to the disk, which would only not be present if the disk is basically a fresh unmagnetized platter from the factory. A disk that has not been nor ever been truly low-level formatted will therefore be physically unreadable. Writing all zeros to all sectors, or any sectors, requires the basic "framework" signaling be written on the disk for the drive controller to be able to find specific sectors.

There was a time in the early to mid 80's before Windows dominance where floppy disks were typically sold "unformatted" - and this low-level format had to be performed for the disk to be useable. The old DOS FORMAT command did the low-level format automatically unless you used the /Q switch for a "quick format" - which was not possible on a never-formatted disk. Linux has separate commands for the low-level (fdformat) and high-level (mke2fs, etc.) format.

The old MFM and RLL hard drives were the same way, but they typically came pre-low-level-formatted from the factory (complete with a sticker listing known defective sectors). But you could perform a true low-level format - one way was to call the low-level format in the controller's ROM directly using the old DOS DEBUG command (http://discussions.virtualdr.com/archive/index.php/t-69312.html). Also read this: http://www.redhill.net.au/d/10.php

IDE drives did not typically provide a user accessible low-level format routine or command and therefore it's not possible to do a true low-level format on these types of drives. You never know what types of diagnostic or debug commands are available on a drive, and what the code on the firmware is capable of doing, but that is the only way a true low-level format would be possible on modern drives.

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Without minding the diagnostic, here is how to low level format your hard drive :

  • /!\ be aware that you will lose everything /!\
  • download UBCD
  • burn the iso (not as a data, burn a CD image)
  • boot on UBCD (often F8 during boot screen, then choose to boot on the CD-Rom)
  • Use arrows in the menu to navigate to Menu 2, Page 4
  • Use MHDD32 or PowerMax to low-level format

It could take 1 to 5 hours, depending on your HDD capacity. Also, on UBCD you have tons of tools that can help you diagnose a hard drive problem.

My opinion is that a low-level format is a last-hope solution. If you have important data, do a back-up. If you don't, continue using your HDD until you lose it, or until you have some money to buy a new one (an old 80 GB doesn't cost a lot -10$?-, you can find it on ebay or in a friend's abandoned computer)

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Check the WARRANTY some hdd have 5 years. Just enter the serial or similar to the manifactors site and it will show if they will replace it or not.

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How do I do a low level format?
There are utilities all over the net that might help you here, but your best bet would be to check with either your laptop manufacturer, or if you know it, the manufacturer of your hard disk and either should have a utility. That being said, it's not going to get rid of the bad sectors.

What do I need to do before trying to do it?
Back up your files. A format is going to wipe out all of your information, so you better be sure you have a backup of what's important, as well as your OS installation disks.

Is there a particular time span until all of the hard disk breaks down and lose all of my data wen it has already bad sectors on it?
It's hard to say. It could be tomorrow, it could be months from now. That's the nature of hardware. There's no set time limit on when a disk could fail or completely fail. Given the fact that you're starting to see bad sectors, you might want to see if you can somehow manage to find a new disk.

How long will a low-level format take, for a laptop with 2Ghz core 2 duo processor and 2Gb ram.
Again, this is hard to say as there are factors in the format. I'd set aside a couple of hours to be safe.

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A low level format won't get rid of bad sectors that are already there and LInux has already told you they've been relocated. If Linux says it's time to replace the disk then you're risking a lot by continuing to use the disk. If you can't replace the disk you don't have any good choices. Since you're going to reformat, where are you backing up your files to?

The low-level format time depends a lot on how big the disk is. If it's a true format with a write/read test afterwards it can take a long time (hours) on a large disk.

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Linux isn't always right about the health of a disk. I once had a disk where the gnome disk utility claimed it was near death but the manufacturer's utility said it was fine. Turned out to be a bug in the gnome tool that affected my drive model. –  bytesum Sep 30 '10 at 14:57
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