In today’s world, information is the most valuable asset. Losing information may cause severe damages, sometimes unrecoverable. This is why organizations are trying to protect themselves against data loss as much as possible by building fault-tolerant systems, employing cloud computing for data storage and implementing complex backup systems. However, sometimes the inevitable happens, and information disappears from the most reliable storage. Understanding the costs and implications of data loss as well as realistically estimating the possibility of restoring the lost data is extremely important in corporate environments.
From practical point of view, all data loss situations can be classified as permanent or reversible. Both permanent and reversible loss of data can be caused by hardware malfunctions, natural disasters, human error and malicious activities. Telling one from another is essential for minimizing the damages.
In a case of permanent data loss, you may be unable to economically recover the data. Thermal and electromagnetic damage (fire, electrical short circuits) and physical breakage are exceptionally rare, but more often than not will render the storage unusable and any data stored on it unrecoverable.
Excessive wear and manufacturing defects are much more often, and will sooner or later happen to nearly every computer user. Fortunately, these situations are often reversible, meaning the data can be extracted in a clean lab.
Logical corruption happens even more often than wear and manufacturing defects. Software problems, human error, operating system malfunctions, power loss during concurrent disk write operations, accidental and malicious user activities can and do cause a lot of damage to data integrity. Fortunately, more often than not information from disks suffering of logical corruption can be recovered almost completely.
An unfortunate exception is with SSD drives. Most modern SSD drives (manufactured in and after 2009) have integrated garbage collection engines that physically destroy information a few moments after it’s been marked for deletion. This behavior is unique to SSD drives and certain high-performance flash drives. Self-destruction of deleted data never happens on magnetic disks that can continue carrying the content of deleted files for months and years after the pointer to a file has been erased from the file system. However, the garbage collection mechanism only engages when a file has been deleted or when a disk is formatted by the operating system. If a logical error causes file system, MBR or data corruption, the self-destruction mechanism will not launch, and the data will remain recoverable.