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