Data Recovery - Who's Who - Buzzwords

Data loss

Data recovery

Disk partition

Head crash

Hard disk failure

Logical damage

Physical damage

"In the field of information technology, data loss refers to the unforeseen loss of data or information. An occurrence of data loss can be called a Data Loss Event and there are several possible root causes. Data loss must be distinguished from data unavailability, such as may arise from a network outage. Although the two have substantially similar effects, data unavailability is temporary while data loss is permanent. Backup and recovery schemes are developed to restore lost data."

"Data recovery is the process of salvaging data from damaged, failed, wrecked or inaccessible primary storage media when it cannot be accessed normally. Often the data is being salvaged from storage media formats such as hard disk drive, storage tapes, CDs, DVDs, RAID, and other electronics. This can be due to physical damage to the storage device or logical damage to the file system that prevents it from being mounted by the host operating system. Although there is some confusion as to the term, data recovery can also be the process of retrieving and securing deleted information from a storage media for forensic purposes."

"In computer engineering, hard disk drive partitioning is the creation of logical divisions upon a hard disk that allows one to apply operating system-specific logical formatting. In layman's terms, partitioning a hard drive makes it appear to be more than one hard drive, especially in how each partition is formatted for different operating systems, and in how files are copied from one partition to another."

"In computing, a hard disk failure occurs when a hard disk drive malfunctions and the stored information cannot be accessed with a properly configured computer. A disk failure may occur in the course of normal operation, or due to an external factor such as exposure to fire or water or high magnetic waves, or suffering a sharp impact, which can lead to a head crash."

"A head crash is a specific type of hard disk failure, and occurs when the read-write head of a hard disk drive touches its rotating platter resulting in damage to the magnetic media on the platter surface (see Hard disk platter)."

"Far more common than physical damage is logical damage to a file system. Logical damage is primarily caused by power outages that prevent file system structures from being completely written to the storage medium, but problems with hardware (especially RAID controllers) and drivers, as well as system crashes, can have the same effect. The result is that the file system is left in an inconsistent state. This can cause a variety of problems, such as strange behavior (e.g., infinitely recursing directories, drives reporting negative amounts of free space), system crashes, or an actual loss of data. Various programs exist to correct these inconsistencies, and most operating systems come with at least a rudimentary repair tool for their native file systems. Linux, for instance, comes with the fsck utility, Mac OS X has Disk Utility and Microsoft Windows provides chkdsk. Third-party utilities such as The Coroners Toolkit and The Sleuth Kit are also available, and some can produce superior results by recovering data even when the disk cannot be recognized by the operating system's repair utility."

"A wide variety of failures can cause physical damage to storage media. CD-ROMs can have their metallic substrate or dye layer scratched off; hard disks can suffer any of several mechanical failures, such as head crashes and failed motors; tapes can simply break. Physical damage always causes at least some data loss, and in many cases the logical structures of the file system are damaged as well. This causes logical damage that must be dealt with before any files can be salvaged from the failed media."