Data Recovery Information
What is Data ?
Files created by a computer user/application for the purpose of analyzing information. It is a work of art, creativity or outcome of any sort of specialization. Data is an invaluable asset. It is the most expensive, in-dispensable part of the computer system. If destroyed it rarely possible to recreate it to its original state.
What is Data Loss?
Data loss can be defined as a situation caused by various known or unknown reasons when file(s) are not visible/accessible in the file system. The causes of this could be many. When data loss occurs, it is widely accepted that it is lost for ever! Data recovery can be done out of most cases of data loss. When data is lost, it is because if is de-linked from the existing file system or the existing file system itself gets corrupted or changed.
The most common causes of data loss are:
Physical Data Loss:
Hard disk drives store data on one or more metal oxide platters. These platters, which spin at a rate of 3600-10,000 revolutions per minute, hold magnetic charges. A read/write head attached to an actuator arm actually floats on a cushion of air, 1-2 micro-inches (one millionth of an inch) above the surface of the platters. Data flows to and from these heads via electrical connections. Any force that alters this process may cause data loss to occur.
More data is being stored in smaller spaces. Ten years ago hard drives stored 40 Megabytes (MB) of data. Today’s hard drives store up to Terabytes (TB) on a smaller surface than the drives of a decade ago. Increasing storage capacities amplify the impact of data loss. As more and more data is stored in smaller and denser areas, mechanical precision becomes crucial.
As a part of this advancing technology, the drive tolerance (distance between the read/write head and the platter where data is stored) is steadily decreasing. A slight nudge, a power surge or a contaminant introduced into the drive may cause the head to touch the platter, resulting in a head crash. In some situations, the data residing in the area touched by the head may be permanently destroyed.
The current tolerance drives is 1-2 micro-inches (millionths of an inch). Comparatively, a speck of dust is 4-8 micro inches and human hair 10 micro-inches. Contaminants of this size can cause serious data damage.
These Physical Data Loss cases include:
• Hard disk not detecting
• Media surface damage
• Bad sectors throughout the disk
• Logic Card Burnt
• Servo motor burn
• Head Crash
Logical Data Loss:
Following are the main reasons of Logical data loss:
• Accidental file deletion
• Computer viruses and worms
• Damage due to a power failure or surge
• Software program failures
• Corrupt or missing critical file system structures
• Partitioning or boot-up problems
• Internal & External Sabotage
• Drives that have been Fdisked or formatted
• Application crash
• System shutdown
• Hard disk or media failure
Data recovery is a process of searching lost data from portions of existing/previously existing file system or from raw sectors and retrieving them with their original structure intact. The most common data recovery process involves the following stages; Analysis of the file system and assembling boot sector, partition table and allocation structures of the system area.
Simulating an intelligent file system from the searched pieces of crashed file system. Searching and linking folders from the disk to the simulated file system. Displaying searched and simulated file system. Saving the selected files to another disk.
More complex data recovery cases require searches and simulations of lost and overwritten partitions or searching for headers / end of file markers of various data files from all sectors of the disk and tagging them as files.
