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Monday, November 21, 2011

Complete Data Recovery From Hard Disk Crash :A Tutorial

Hard disk crash is one of the worst nightmare of computer users.It can happen at any moment or at any time, means it is not certain when it will occur.I created this tutorial because my portable hard disk was crashed two times and when I asked the experts some advised to format it and some demanded huge sum of money for recovery.So I decided to find the solution.
Light bulbA hard disk crash can occur by any of the following reasons:
  1. Virus
  2. High voltages,Current leak
  3. Problem in usb port in which you connect your pen drive or External Hard Disk
First cause is not too severe and can be corrected very easily but other remaining two may cause the disk/Pendrive to be of almost no use.It could damage the internal circuitry of the Pendrive and in case of Hard Disk read/write head starts crashing with disks.
Problem of Virus: If Hard Disk/Pen Drive shows its size but you are unable to access it directly then It could be the problem of virus.In this case scan it from a good but updated antivirus and then follow the recovery procedure.
For the Hard Disk:If scratching sound comes from your hard disk and It is inaccessible too then do not retry again again to use the drive continuously rather stop using it and use only it for recovering the data(I will discuss how to recover the data later in this tutorial).After you have successfully recovered your data from it and saved it to another drive replace your drive if it is in its warranty period.
For the pendrives: If problem occurred due to 2nd or 3rd case then in 90% cases Pendrive is damaged completely and only way is to get it replaced by your vendor.This case happened to me more than 5 times and I replaced my pendrive each time and got a new one Smile.
Recovery: Now I will discuss how to recover your data from a crashed hard disk/Pendrive.
Windows provides great in built tools for this purpose.So first try them before going to buy any third party proprietary tools.
chkdsk: You might have used this command before via right clicking your drive –>tools--->select the first option:Error checking.
But I would recommend the command line version since your Hard Disk/Pendrive may not be visible and If it is visible It would take too long to respond when you will right click on it.
So better to switch to command line and follow the steps:
  1. Open the command prompt with administrative privilege i.e “Run as administrator”
  2. Run the chkdsk with following switches
  3. chkdsk  [driveletter:] /F /R
  4. Clock wait for the five stages to complete.
recover1Run the above step two times for proper recovery.*you can leave the option /R if you just want to fix the errors.This command works by removing the bad sectors by chaining i.e if a sector is bad then all data at that sector is copied to another position and all references to that bad sector are transferred to new sector.This scheme is known as sector sparing or forwarding.
Light bulbA typical bad-sector access might be as follows:
1.The operating system tries to read logical block 63.
2.The controller calculates the Error Correcting Code and finds that the sector is bad.
3.It reports this finding to the operating system.
4.The next time the system is rebooted, a special, command is run to tell the Hard disk controller to replace the bad sector with a spare.
5.After that, whenever the system requests logical block 63, the request is
translated into the replacement sector's address by the controller.recover blogpost
Third Party Tools: You can also use the third party tools to recover your data.
Some popular ones are:
  • Acronics Disk Director Home
  • Active File Recovery
  • Seagate File Recovery
  • iCare Data Recovery

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