| Data Loss Is Not A Small Thing | | | | secondary media, preferably removable media that |
| The impact of a data loss on a business can be | | | | can be stored in a separate location. You can then |
| visualized if you consider a manufacturing operation | | | | restore the system or the data from these backup |
| with over a thousand employees, whose pay details | | | | copies in case of a data loss. |
| are kept in the company’s computer system. | | | | While in theory, backup is a foolproof safeguard; in |
| Imagine what could happen if these pay details | | | | practice things are quite complex. First comes the |
| become inaccessible owing to system problems, | | | | organizational aspect. |
| operator errors or a malicious virus attack. | | | | - Taking backups after every change |
| Reconstructing the details is not going to be a | | | | - Selecting the media to store the backup, having |
| short-term operation. | | | | regard to the costs and recovery steps involved |
| Yet such reconstruction is unavoidable not only to | | | | - Keeping track of what data is on what media and |
| pay the employees correctly but also to comply with | | | | which are the latest ones |
| regulatory requirements under employment and | | | | - Auditing the backup procedures and media to |
| taxation laws. The cost of such a reconstruction is | | | | ensure that they are indeed reliable |
| going to be a major expense item for the company, | | | | Numerous options are available for backup. |
| not to mention the disruption to business operations. | | | | - Media for storage could be magnetic tapes (least |
| On the other hand, if the company had taken proper | | | | expensive but slow retrieval), hard disks (fast |
| actions to make recovery of the lost data possible, | | | | retrieval possible but was comparatively quite |
| the time, business disruption and money costs would | | | | expensive until recent times) |
| be insignificant compared to a complete | | | | - Data could be backed up fully, or incrementally, or |
| reconstruction from scratch. | | | | continuously, with different cost and recovery |
| How Data Gets Lost | | | | implications |
| An awareness of the different ways data could get | | | | - The backed up data could be stored in a way that |
| lost should be the starting step in organizing your | | | | enables immediate online access or in offsite vaults or |
| defenses. So we look at these first. | | | | disaster recovery centers |
| Data stored on a computer disk can be lost in | | | | - Remote third party backup services could be utilized |
| several ways. | | | | getting the benefit of their expertise and facilities |
| - User Action | | | | The above options are actually only illustrative. There |
| - The computer user deletes a data file or computer | | | | are more options and sub-options available to suit |
| program thinking that it is no more needed. It could | | | | different requirements. The availability of the options |
| later turn out that the deletion was premature. | | | | and their different implications make selection of a |
| Accidents | | | | backup policy a complex exercise. |
| - User deletes file or program, but not with full | | | | In practice, backup is mostly unsatisfactory in |
| awareness of what he is doing. For example, a | | | | implementation and far from adequately dependable. |
| blanket deletion of a large number of files could result | | | | RAID: RAID through hardware or software |
| in deleting some important files that the user would | | | | implements redundant storage so that the failure of a |
| not have consciously deleted. | | | | single disk does not result in data loss. RAID |
| - The files or programs were stored on removable | | | | implementations have different levels with different |
| storage media like floppy or compact disks or USB | | | | degrees of safeguards against data loss. RAID is not |
| drives that were misplaced and could not be found | | | | only a data loss safeguard; it is a means for higher |
| when needed. | | | | speed data access. |
| - Errors made by network administrators and other | | | | Journaling: An apparently single write operation |
| administrative persons could lead to the loss of | | | | actually involves several write operations. If some |
| important files or programs that their users might not | | | | disturbance prevents one of these several operations |
| have deleted. | | | | being completed, the result would be invalid data. One |
| System or Infrastructure Problems | | | | remedy against such an event is maintaining a journal |
| - Power could fail before the data could be saved to | | | | of all changes before actually doing the write |
| permanent memory and the user might be unaware | | | | operation. If the write is not completed successfully, |
| that it has not been saved. | | | | the operation can be replayed using the journal and |
| - Different kinds of hardware failure, such as contact | | | | completed successfully. |
| between the read-write head and the rotating disk | | | | Antivirus: Practically every computer user would have |
| platter in a hard disk drive (in normal operation, there | | | | by now become familiar with antivirus software that |
| is a minute cushion of air between the two), could | | | | helps you prevent virus attacks and even recover |
| lead to the data on the disk becoming unreadable. | | | | any damage done by such attacks. |
| - Software crashes, as when an application or the | | | | Firewalls: Firewalls act as a barrier between networks |
| operating system suddenly gets stuck halfway | | | | of different trust levels. The Internet is a network of |
| through a work session, could result in the work not | | | | no trust level while an internal network has a higher |
| being saved. | | | | trust level. A firewall could control the data flow |
| - Data corruption as when the file system or | | | | between the networks by either allowing only |
| database gets corrupted and the data in the files or | | | | previously allowed network connections or preventing |
| database becomes unreadable, or when unintended | | | | specifically blocked connections. In practice, firewall |
| changes during transmission or retrieval results in | | | | implementation tends to be inefficient. |
| erroneous data. | | | | User Education: Considering the fact that user errors |
| External Factors | | | | are a major factor for data loss, proper user |
| - A natural disaster like an earthquake, flood or | | | | education could go a long way in preventing data loss. |
| tornado destroys the equipment including the data | | | | Data Recovery |
| storage media. | | | | Expert data recovery consultants could recover much |
| External Interference | | | | of the “lost” data not only because of |
| - A worm or virus attack results in damage to data | | | | their specialized training and experience but also |
| - A hacker intrudes into the system and erases | | | | because they have the necessary facilities, such as |
| damages the data | | | | Class 100 Clean Rooms kept free of dust. Even |
| - A thief steals the physical media | | | | minute specks of dust could make the thickly packed |
| Of the above, hardware failure and human errors | | | | data on disks unreadable. |
| reportedly account for 75% of the incidents. Data | | | | These companies use techniques like repairing the file |
| loss through natural disasters is rare. However, if that | | | | system damage so that the image on the disk could |
| happens, there is no way to recover the data unless | | | | be deciphered as meaningful data, replacing damaged |
| you had stored backups in a physically separate | | | | PCBs or read-write heads with matching, healthy |
| location. | | | | ones, removing the platters from the damaged drive |
| Let us now look at ways to minimize data loss. You | | | | and installing them in a healthy drive or a combination |
| can only minimize it; absolute protection even against | | | | of these measures. |
| minor losses is impracticable. | | | | It would be apparent that these are procedures |
| We also look at the possibilities of data recovery if | | | | requiring high precision, considerable expertise and |
| data does indeed get lost. | | | | specialized facilities. Attempting to do it in-house is |
| Organizing Against Data Loss | | | | only likely to make the data completely irrecoverable. |
| Backups: You copy all data and programs to a | | | | |