Data Loss and Recovery

In all areas of life, in all types of industries, data is a key to success, valuable asset. Unfortunately this priceless asset  is susceptible to a vast array of potential memory loss factors. Data lost event can occur any time for many reasons. In the field of information technology, data loss refers to the inability to access any data from a previously functioning computer system or backup.

Types of Data Loss Events

• User Action
  • The computer user deletes a data file or computer program thinking that it is no more needed. It could later turn out that the deletion was premature.
• Accidents
  • User deletes file or program, but not with full awareness of what he is doing. For example, a blanket deletion of a large number of files could result in deleting some important files that the user would not have consciously deleted.
  • The files or programs were stored on removable storage media like floppy or compact disks or USB drives that were misplaced and could not be found when needed.
  • Errors made by network administrators and other administrative persons could lead to the loss of important files or programs that their users might not have deleted.
• System or Infrastructure Problems
  • Power could fail before the data could be saved to permanent memory and the user might be unaware that it has not been saved.
  • Different kinds of hardware failure, such as contact between the read-write head and the rotating disk platter in a hard disk drive (in normal operation, there is a minute cushion of air between the two), could lead to the data on the disk becoming unreadable.
  • Software crashes, as when an application or the operating system suddenly gets stuck halfway through a work session, could result in the work not being saved.
  • Data corruption as when the file system or database gets corrupted and the data in the files or database becomes unreadable, or when unintended changes during transmission or retrieval results in erroneous data.
• External Factors
  • A natural disaster like an earthquake, flood or tornado destroys the equipment including the data storage media.
• External Interference
  • A worm or virus attack results in damage to data
  • A hacker intrudes into the system and erases/damages the data
  • A thief steals the physical media

 Data Loss Recovery

Backups: You copy all data and programs to a secondary media, preferably removable media that can be stored in a separate location. You can then restore the system or the data from these backup copies in case of a data loss.

Can You Really Count On Your Backups

While in theory, backup is a foolproof safeguard; in practice things are quite complex. First comes the organizational aspect.

• Taking backups after every change
• Selecting the media to store the backup, having regard to the costs and recovery steps involved
• Keeping track of what data is on what media and which are the latest ones
• Auditing the backup procedures and media to ensure that they are indeed reliable

Numerous options are available for backup.

• Media for storage could be magnetic tapes (least expensive but slow retrieval), hard disks (fast retrieval possible but was comparatively quite expensive until recent times)
• Data could be backed up fully, or incrementally, or continuously, with different cost and recovery implications
• The backed up data could be stored in a way that enables immediate online access or in offsite vaults or disaster recovery centers
• Remote third party backup services could be utilized getting the benefit of their expertise and facilities

The above options are actually only illustrative. There are more options and sub-options available to suit different requirements. The availability of the options and their different implications make selection of a backup policy a complex exercise.

In practice, backup is mostly unsatisfactory in implementation and far from adequately dependable.

Data Recovery:

Recovering a single lost file is going to be hugely different than recovering a whole system. When restoring data from backup doest not gaurantee the full recovery   or imposible to implement then  there are  commercial services that provide data recovery service from physically damaged media.

These companies use techniques like repairing the file system damage so that the image on the disk could be deciphered as meaningful data, replacing damaged PCBs or read-write heads with matching, healthy ones, removing the platters from the damaged drive and installing them in a healthy drive or a combination of these measures.

It would be apparent that these are procedures requiring high precision, considerable expertise and specialized facilities. Attempting to do it in-house is only likely to make the data completely irrecoverable.