Despite the constantly growing reliability of storage devices, the loss of digital information remains quite commonplace. The frequent causes of data loss include human errors, software malfunctions (such as computer viruses), power outages as well as hardware failures. Luckily, the information stored on a digital medium is almost always recoverable. The following article explains what data recovery is, describes the most common data loss problems and ways of addressing them.
Data recovery can be defined as a process of obtaining the information located on a storage device that cannot be accessed by the standard means due to its previous deletion or certain damage to the digital medium. Different approaches are used to regain the missing files, yet, only on the condition that their content is present somewhere within the storage. For instance, data recovery doesn’t cover the situations when a file has never been written to a persistent storage, like documents that were created but could not be eventually saved to the hard disk drive due to a power failure. Also, none of the existing recovery methods can cope with the cases of permanent erasure of data which occurs when some other information occupies its storage space – under such circumstances, the lost files can only be restored from an external backup.
In general, data recovery techniques are divided into two types: software-based and ones involving the repair or replacement of the damaged hardware components in a laboratory setting. A software-based approach is employed in the majority of cases and involves the use of specialized utilities able to interpret the logical structure of the problem storage, read out the required data and deliver it to the user in a usable form for further copying. Physical repairs are conducted by specialists in the most severe instances, for example, when some mechanical or electrical parts of the drive no longer work properly – in this case, all the measures are directed towards a one-time extraction of the critical content, without the possibility of continued usage of the affected device.
The most typical cases of data loss
By and large, the overall success of a data recovery procedure depends heavily on the choice of the right recovery method and its timely application. That is why it is highly important to understand the nature of the data loss instance and know what can be done in each specific scenario. In contrast, the wrong actions can lead to the irreversible destruction of the information.
The most common causes of data loss include:
- Accidental deletion of files or folders
Each file system acts differently when deleting a file. For instance, in Windows the FAT file system marks file directory entries as “unused” and destroys the information about the allocation of the file (except for the beginning of the file), in NTFS only the file entry is marked as “unused”, the record is deleted from the directory and the disk space is also marked as “unused”; most Linux/Unix file systems destroy the file descriptor (information about the file location, file type, file size, etc.) and mark the disk space as “free”.