Data Recovery

Data recovery is the process of restoring data that has been lost, accidentally deleted, corrupted or made inaccessible. In Information Technology Enterprise, data recovery typically refers to the restoration of data to a phone, desktop, laptop, server or external storage system from a backup.

The most typical cases of data loss

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".

File system formatting can be started by mistake, for example, as a result of specifying a wrong disk partition or on account of mishandling a storage (e.g. NAS devices usually format the internal storage after an attempt to reconfigure RAID). The formatting procedure creates empty file system structures on the storage and overwrites any information after that. If the types of the new and the former file systems coincide, it destroys the existing file system structures by overwriting them with new ones; if the types of the file systems differ, the structures are written to different locations and may wipe the user’s content.

Modern file systems have a high level of protection against internal errors, yet, they often remain helpless against hardware or software malfunctions. Even a small piece of wrong content written to a wrong location on the storage can cause the destruction of file system structures, breaking file system object links and making the file system non-readable. Sometimes, this issue may occur due to blackouts or hardware failures.

This failure may occur because of a failed "fdisk" operation or user's errors, which usually result in the loss of information about the location and size of a partition.

If you suspect any physical issues with the storage (e.g. the device doesn't boot, makes unusual noises, overheats, faces problems with reading, etc.), it is not recommended to perform any data recovery attempts on your own. You should take the storage to a specialized. If a failure has occurred to a RAID system (failure of one drive in RAID 1 or RAID 5, failure of maximum two drives in RAID 6, etc.), restoration is possible without the missing drive, as the redundancy of RAID allows recreating the content of a failed component.

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