Once data has been captured in a computer system, it must be stored securely and made available to users when they need it. Data must also be maintained and used so that its integrity is not compromised.
There are two main components to ensuring availability of data and thereby minimising the risk in entrusting valuable data to technology. These are ensuring that systems operate to deliver data as needed, and backing up data to guard against system failure or data loss.
Making data available
Making data available to users is one of the main purposes of a computer system. At the same time, however, ensuring the integrity of data is of key importance. Only those users with a 'need to know' should have access to data, particularly when it is of a sensitive nature. Access to data can be restricted by using passwords and controlling access rights by login permissions (see Data Access Security).
Even where users have a need to access data, not all users will need to change data. Again, login access permissions and passwords can be used to limit those users who are able to change data to those who have a need to do so. Where users are permitted to change data, verification techniques can be used to minimise the chance of errors occurring (see Ensuring Reliability of Data).
Security measures can also be employed to prevent unauthorised users gaining access to data (see Security).
See the following topics for other relevant issues:
Data backup
The final safeguard against system failure and loss of data is data backup. Regular back up can mean taking these precautions at least once each working day, more often if crucial data is being collected, such as during an electoral event. Data can be backed up on a wide variety of formats - removable disks of various kinds, multiple hard disks, or magnetic tapes, for example.
The organisation's overall information technology strategy can document a formal backup regime. Ideally, data backup can be automated to ensure that human error does not cause problems. However, regular checks of automated backups will still be necessary to ensure that computer error does not also cause problems.
'Live' data can be backed up as it is created, by use of mirrored hard disks, which could be located on the same server or on separate servers. Using mirrored disks, the same data is simultaneously stored on two or more disks. This means that if one disk fails, data can be restored from the other. It is preferable to use separate servers for mirrored disks, as a second server can be used if the first server fails completely.
Software programs, both commercial programs and those developed in-house, can also be backed-up so that they are available to reload if the production versions of the programs are lost or corrupted. Most programs come loaded on disks. Increasingly, however, programs can be downloaded from the internet. In this case backup copies should be stored locally, as there is no guarantee that the same programs will be available on-line in the future. Program disks that are stored in a data library and managed by a responsible officer or staff unit can then be easily located and used if necessary.
Care should be taken, when backing up program data, that software licences are not breached. Most licences include permission to keep backup copies of software.
For more information on data maintenance strategies see Maintenance.
