File deletion

• Freeing the disk space
• Removing duplicate or unnecessary data to avoid confusion
• Making sensitive information unavailable to others
• Removing an operating system or blanking a hard drive

Accidental removal

A common problem with deleting files is the accidental removal of information that later proves to be important. A common method to prevent this is to back up files regularly. Erroneously deleted files may then be found in archives.

Another technique often used is not to delete files instantly, but to move them to a

The common problem with sensitive data is that deleted files are not really erased and so may be recovered by interested parties. Most file systems only remove the link to data. But even overwriting parts of the disk with something else or formatting it may not guarantee that the sensitive data is completely unrecoverable. Special software is available that overwrites data, and modern (post-2001) ATA drives include a secure erase command in firmware. However, high-security applications and high-security enterprises can sometimes require that a disk drive be physically destroyed to ensure data is not recoverable, as microscopic changes in head alignment and other effects can mean even such measures are not guaranteed. When the data is encrypted only the encryption key has to be unavailable. Crypto-shredding is the practice of 'deleting' data by (only) deleting or overwriting the encryption keys.

See also

• Crypto-shredding
• Data erasure

References