Recovering data after logical damage

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 XDisk Utility and Microsoft Windows provides chkdsk. Third-party utilities such as The Coroners ToolkitThe Sleuth Kit are also available. Even deleted data is also considered to be logically damaged drive for example due to virus attack, if you format the drive or accidental deletion. has and

Some kinds of logical damage can be mistakenly attributed to physical damage. For instance, when a hard drive's read/write head begins to click, most end-users will associate this with internal physical damage. This is not always the case, however. Sometimes, hard drives can click simply when the drive is not getting enough power - which often occurs on USB-powered drives. Another possibility is that the firmware of the drive or its controller needs to be rebuilt in order to make the data accessible again.