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Recovering Data from a Physically Damaged Drive |
The Symptoms
The computer shows several signs which may indicate that the hard disc has been affected in a negative way. The most obvious symptom is the inaccessibility of the hard disc. If the drive refuses to respond to all softwares like BIOS, Windows Desk Management and other disk utilities, it will be understood that the problem is beyond scandsk or chkdsk, and the computer might be headed for a graveyard. A dead drive may also not spin, or it may emit clicking, beeping or other unfamiliar noises. A disc crash is a major matter, and home users are advised to check all other possibilities -- like bad connection to the main power supply, connection to the CPU, and other physical factors thoroughly before raising the alarm.
The Causes
The causes for a physical loss of data can be summarised as follows:
Fire and Water: In the case of accidents like fire or flooding, the chances of recovery are slim, but not entirely nil. Sometimes, it is advisable to keep a hard drive affected by water in a wet condition, because the water may corrode the metal while drying. Some experts advise exactly the opposite. Discs are much more resilient now when it comes to higher temperatures, and can stand up to 770 degree Celsius (Curie temperature) beyond which the iron will simply melt.
Excessive Humidity: This can also affect a disc, especially if it has been removed and stored carelessly under uncontrolled climactic conditions.
Dust: Exposure to dust for a long time or in high quantities will damage a disc. The dust particles gather in the ‘crevices' of the drive's surface and literally corrode the information.
Impact: Once again, the laudable improvements of a disc's durability must be mentioned. A drive can stand up to 300G of shock -- which is truly amazing. But if the vertical component of the drop is greater than the speed at which a read head moves, then the surface may be fatally scarred, and the data won't be readable any more.
Damaged components: A damaged electronic board, malfunctioning heads, motor failure, mother board defects, and several other hardware-related problems can cause physical damage to data. It can be as ‘small' a matter as a fan that is not working properly, but the implications can be very big indeed if the machine gets overheated.
Recovery
Physical data loss has a lower recovery rate than logical loss. It is also often extremely expensive. A data recovery firm has the facility of a Clean Room, which is a chamber with stringently controlled atmospheric conditions, and a negligible amount of dust particle content. Here, the disc is taken apart, and checked for damage. If a head or some other part is to be replaced then the fresh piece is put in while the disc is in this regulated environment. There are other methods that can be applied -- all depending on the damage done. One technique is MFM (Magnetic Force Microscope) photography. As the name suggests, this is a photograph of the different zones of a drive depicting the magnetic impulses, in other the ‘portraits' of the data. These photographs, when joined together, give the total picture of the drive, and one can physically see the damaged areas. If this sounds simple, a few statistics can break up the concept. A 20 GB disc contains 160,000,000,000 bits, with an average overhead of 300,000,000,000 more bits. Each of these bits presents a magnetic flux of some sort. Tracking the problem through this maze can be like looking for the proverbial needle in the haystack. Needless to say, the people who undertake to do this process deservingly charge very high.
The Decision
Ultimately, the value of data depends on the user. If it is important and worth the pains, then one has to swallow the time and cost factors. But if it is really not that crucial, or if there is enough backup to rebuild what is lost, then one can count oneself lucky, and implement the lesson learnt through the present loss for a safer future.
Article source http://w4rum.com/2258.t
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| [By Kimber Fulcher] [05/May/07] |
