Data recovery is the process of retrieving data from corrupted or damaged storage media when it cannot be accessed. The storage media in question will often be a hard disk, but it can also be removable media such as CDs, DVDs, Blu-rays, and storage tapes. There are many different reasons why a system administrator may need to use data recovery tools.
At boot up, mainstream Linux distributions perform routine scans to identify and fix any inconsistencies in the file system. A damaged file system might be caused by the computer not shutting down in an orderly fashion, which can occur say in the event of a power cut. However, such routine scans will not detect hardware failure which might exist for a long period without being noticeable to users. Accesses to bad sectors on the media can make the situation worse, and with further usage as well as the passage of time, the media can eventually become unreadable.
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