Logical errors are one of the primary causes leading to data loss. The different types of logical errors that can occur are -- deleted files, read/ write head failure, file corruption, hard drive crash, corrupted programs, deleted partitions, reformatted hard drives and faulty backup software.



Missing Operating System

If the operating system resides on the drive or partition that has experienced hard disk failure, then the computer will not boot. This is classified as a logical disk failure. This is usually characterised by a blue screen, a blinking cursor on the monitor or a message ?missing operating system?. Users can experience data loss due to the operating system failure.

File Fragmentation

File system fragmentation, also referred to as file system aging, refers to the inability of a file system to lay out related data sequentially. File system fragmentation increases disk head movement or ?seeks?. Usually, when fragmentation occurs, it is de-fragmented by compressing files and free space back into contiguous areas.

Head Crash

A head crash is an extremely frequent phenomenon and always leads to data loss. It occurs mostly because of how precariously aligned it is. A series of hard disk platters rotate at the rate of 150 times per second. Even the slightest disturbance inside the disk could cause the entire disk to stop functioning properly. When the read/ write head touches the rotating platter of a hard disk, it leads to a head crash.

Partition Deletion

Before data can be stored on a hard disk, it needs to be partitioned. A partition is an area of the hard disk that is set aside for use by an operating system. All operating systems need to have at least one partition to write data to. Writing to an unpartitioned disk is impossible. The Master Boot Record contains the boot code that is required to start a computer. All primary partitions are defined in the MBR's partition table. Though the Master Boot Record and the partition tables are just a few sectors, they are vital and if they are damaged, it will lead to data loss.

When a partition table is corrupted or deleted, it affects access to entire partitions or even the entire hard disk. Even accidental partition deletion will make data in that partition inaccessible. To recover the lost partitions, special data recovery software is required. This software will locate the lost partitions and reconstruct the partition table. It is important to use the correct recovery software to prevent further permanent damage.

Electrical Failure

Electrical failure is another reason that can lead to data loss. It is the direct effect of the circuit board failure, located at the bottom of the hard drive. Faulty components, electro-static discharge and damaged circuitry during installation are some of the various reasons that cause electric failure. To prevent this, it is important to keep the system in a clean and cool, well-ventilated place.

Virus Attacks

A computer virus is a program that can copy itself and infect a computer without the knowledge of a user. The original may modify copies or the copies may modify themselves. A virus can spread from one computer to another, when its host is taken to the uninfected computer. Viruses can also spread to other computers through a network file system. Some viruses are programmed to damage the computer by damaging programs, deleting files or reformatting the hard disk. Typically, they take up computer memory used by legitimate programs. Viruses are also bug-ridden, which lead to system crashes and data loss.

The solution to a virus attack is to use anti-virus software applications. Anti-virus software is rampantly available in the market. While there are software that will detect and clean up after a virus attack, the best preventive method is to have an anti-virus-software installed beforehand.

Overwriting

While most other logical problems can be rectified and data retrieved, overwriting is the one logical problem that can lead to permanent data loss. In fact, when users want to dispose off old computers and want to ensure confidential data is completely erased, they use overwriting as the method of permanent data deletion.

Conclusion

Logical failure can occur at the most unlikely times. Therefore, it is important to always take backups of data that is stored on the computer. Backup of data has to be carried out on a regular basis in order not to suffer data loss, in the event of a failure. Even otherwise, data recovery is possible using special software but it can be time-consuming and quite expensive.