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v5: Imaging disks with bad sectors

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v5: Imaging disks with bad sectors



This article explains how to image and recover a disk that has developed bad sectors. A disk that has bad sectors is permanently damaged and, if the bad sectors were in use by the file system, it is very likely that the data contained in the damaged area is unrecoverable.

This may be a sign that your hard drive is coming to the end of its life, though, it is still possible to manage the situation and create an Image whichcan be restored or used to mount and copy files and folders.  

For more information on bad sectors please see this Wikipedia article http://en.wikipedia.org/wiki/Bad_sector


Detecting bad sectors

If a bad sector is encountered during image creation then you will receive the following error in your backup log:

Backup aborted! Unable to read from disk - Error Code 23 - Data error (cyclic redundancy check)

Note: This is considered a fatal condition because your data cannot be read and the image will abort. 

The first step should be to run 'chkdsk' on the problem drive to reallocate file system clusters to undamaged disk sectors.


Run chkdsk so bad sectors are not within the file system

Run 'chkdsk c: /r' from a command prompt. Replace 'c:' with the appropriate drive letter.

Note:
The '/r' switch is important and will cause the entire file system to be checked for bad sectors. This will require a reboot to complete and may take some time.

To open a command prompt:
  • In Windows XP and Server 2003: Click 'Start' > 'All Programs' > 'Accessories' > 'Command Prompt'.
  • In Vista/7/8 and Servers 2008/2011/2012 follow steps from a.
    (Note: if at START screen in Windows 8 start at b.)
    1. Press keyboard ‘Windows key’
    2. Type word 'command'
    3. Then right-click on ‘Command Prompt’
    4. From menu click 'Run as administrator' (in Windows 8, menu is at bottom of screen)

Enter 'Y' if you receive the 'schedule this volume..' message.

The above will map out any bad sectors in use by the file system.  After doing this immediately create an Image of your drive. This will ensure that all file system clusters are located on good sectors.  It's important to realize that you have already lost data if clusters are relocated, as the data contained in them is unrecoverable. You should consider replacing your disk. 

Note: If you still receive 'Error Code 23' in your log after running chkdsk then run chkdsk repeatedly until an image can be created without error.

A list of bad clusters is stored in the file system and is copied when you create an Image and when you restore the Image. After restoring an Image to a new disk, if you are running Windows Vista or Windows 7, then run 'chkdsk c: /b'which will re-evaluate all the bad clusters restored on your drive andremove non-faulty clusters from the list. If you are running Windows XPthen if you boot into the Windows PE rescue CD you can run the samecommand from there.  /b only works with NTFS volumes.


Force Macrium Reflect to ignore bad sectors

If you are unable to successfully reallocate file system clusters by running chkdsk then you can force Macrium Reflect to continue on Error 23.

Take the 'Other tasks' > 'Edit defaults' > 'Advanced' option and select 'Ignore bad sectors', click 'OK'. Images will now complete:

Note: The bad sectors will be reported in the Image log, e.g:

Read Error: Bad sector found in cluster 2353222
Read Error: Bad sector found in cluster 2353223



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Last Modified:16 Dec 2013

Last Modified By: Administrator

Type: Tutorial

Level: Intermediate

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