Tuesday, May 7, 2013

Bad sectors on a Mac hard drive and file-based recovery

Data recovery applications are life saver tools and best at what they do, i.e. regaining lost, deleted and formatted data including multimedia, office & other type of files from a crashed/corrupted hard drive. But, Is recovering the data from a drive always as simple as we may think of it? Yes, perhaps if we are talking about a case of perfectly fine drive having no physical issues, bad sectors etc. On contrary, retrieving any type of files from a hard drive or other storage device acquiring bad sectors is not only a tiresome task but also an absolute challenge for the recovery software to prove its effectiveness. Despite challenges and complexities involved in acquiring back the data from a bad drive, the user and the data recovery application needs to be synchronized with correct form of techniques that ensure maximum percentage of data that can be recovered or even 100% in few exceptional cases.

The data recovery apps do work like magic but the result delivered to the user is highly dependent upon the deleted data left-overs on the hard drive blocks, physical status of the drive and of-course the algorithms of the recovery tool in use”
How can you identify bad blocks or internal miss happening on the drive:
  • Consider your drive not to be fully fine, if you hear an abhorrent sound when the drive is spinning.
  • You may also hear the drive rotation with added sound effects upon accessing a particular application.
  • Frequent system crashes, same application crashes again and again even after its installation and compatibility being OK.
  • Unable to successfully complete read-write operations on a file located in bad-blocks of the device. Consider a simple case of data transfer being halted every time you try to copy data from an external storage device to your computer.

    [Also Read:Review: Disk Drill data recovery app for Mac]
Bad Sectors Found on Drive. What's Next?
Any of the above issues encountered on your Mac drive on a regular basis can put this in confirmation – 'Yes, my drive does have bad sectors'. The next big question is to recover all the files and folders from the bad hard drive and put the drive under 'To Repair' list. So, the time is right to scan the bad drive with the help of a data recovery software and 'Thanks Goodness', there are plenty of options available. But, remember, here we are focusing more on the right procedure to acquire the data from a bad drive.
  • Install a data recovery application and launch it.
  • Upon launching the tool, few basic options are highlighted, for time being, please ignore the 'Recovery' options and instead locate the 'Create Image' button.
  • The create image options are available for the situations when the drive is not suitable for a normal scan due to presence of large no. of bad sectors. Click Create Image<<Select the drive, proceed<<Choose a destination to save the .DMG file. {Please make sure the destination drive capacity is larger than the source.}
  • Now, load the image file of the drive and perform 'Quick Scan' to regain all files and folders back.
Logic? In the above steps, there is a simple logic used by the recovery software. By creating the image of the bad drive, the software copy all the data present on good sectors of the drive and jumps over any bad block encountered in-between. This way, the image created for further scan is the one having data from all the good sectors of the drive.
Pros of Imaging & Recovery
  • Imaging takes all the data from good sectors leaving the bad ones. In case the drive fails, the user is still left with the good sectors data rather than having nothing.
Cons of Imaging & Recovery
  • Imaging a hard drive is time taking process and may stretch to long hours if the drive size is in Tera bytes.
RAW Recovery: This is another tested and successful method of making recovery possible from a bad hard drive. The raw recovery locate the files on the entire drive (both good & bad sectors) through file signatures. Signatures are nothing but the extensions of the files e.g. .docx for MS Word, .pdf for PDF, likewise. The functionally of the RAW recovery is also similar to the above applied LOGIC. The ra

w recovery scans the entire bad drive and regains the data from good sectors, jumps over any bad sectors that is encountered.
Pros of Raw Recovery: Advance recovery option when all recovery methods seems to be useless.
Cons of Raw Recovery: A file already in corrupted state will also be recovered by the raw recovery, but even after the recovery, user might complain about the file corruption. Raw Recovery is time consuming deal that can stretch to hours of scanning.

1 comment:

  1. I would like to thank you for the efforts you have made in writing this article. I am hoping the same best work from you in the future as well. In fact your creative writing abilities has inspired me to start my own BlogEngine blog now. Really the blogging is spreading its wings rapidly. Your write up is a fine example of it.

    UK IT Distribution