Data stored in electronic media (like hard disks, tapes, etc) is prone to failure either due to mechanical, electrical or software problems. And such failure leads to data loss.
Data retrieval is the attempt to retrieve lost data from an electronic medium that has been damaged. Data recovery can be categorised into physical and logical data recovery.
Extracting data from media affected by mechanical failure (like a head crash, failed motor) or an electronic failure is physical data recovery.
While data extraction after data has been lost due to virus attacks or accidental file deletion is logical data recovery.
Quite frequently physical data recovery is followed by logical data recovery to retrieve the entire data. 85% of all data lost can be recovered. However, every computer user panics when faced with data loss. Results of a study established that 7% of panicked users hit the computer while some 20% of them sit down and cry. These are ignorance-based, fear-induced, reactions.
Data that can be Recovered
Physical Data Recovery
Data can be recovered from damaged hard disks. But, physical data recovery must be attempted only in a class 100 clean room to prevent dust and other contaminants settling on them. Professional experts replace the damaged parts with good working parts from a healthy drive. The platters are removed and placed in a healthy drive and thus attempt to recover lost data.
Logical Data Recovery
70% of the data is lost due to a logical damage of the computer. Logical data recovery can be attempted by the individual pc user by using data recovery software.
Data recovery software should not be run on the same drive from which data has to be recovered. For, it might overwrite the existing data. It should be run from a C disk or a floppy. Once the lost data is located, the user can attempt retrieval if its quality proves satisfactory.
Data that cannot be Recovered
All lost data cannot be recovered.
If the hard disk falls on the ground, the platters get unbalanced. When the computer is powered on the vertical vibration of the unbalanced platters will cause the read head to crash into the platters. This will damage the magnetic layer and lead to data loss. Such damaged media surface presents very minute chances of data recovery. There is no known technology to balance the unbalanced platters and recover data.
Even in the case of physical data recovery, it is not always possible to replace the damage parts. Modern hard drives are conditioned to work in perfect coordination after they have been assembled. Therefore, even if two drives share the same number their parts cannot be interchanged.
Data recovery is also not possible when fire ravages the hard drive and the magnetic coating on the platters is completely demagnetised.
But data recovery from fire-damaged disks is also possible sometimes. This was proved by the fire victims in 2005. 350 houses were ravaged by fire and data recovery experts were able to retrieve data in many cases. Fire damages the plastic casing of the computer completely. The metal hard disk that contains the data presents possibilities of a recovery. Data retrieval is dependent upon the extent of the damage. However, a recovery can never be guaranteed in such cases.
Fire damages in a two-fold manner. The fire is followed by the water poured from hose pipes. Computers are first exposed to the intense heat and then to the damages caused by water. Computer users need not worry for such natural disasters are responsible for just 2% of data loss.
Data Security