Computer systems do not look after themselves - they have to be maintained. Computer systems maintenance can be divided into three broad categories:

• Hardware maintenance
• Systems maintenance
• Maintaining information

Hardware Maintenance

The organisation's overall information technology strategy could document a hardware maintenance schedule. Each item of hardware will likely require routine maintenance. The manufacturers or suppliers of hardware generally provide instructions on the maintenance needs of each item of hardware.

Responsibility for routine maintenance can be set out in the information technology management structure. It is preferable (and in many cases essential) that maintenance be carried out by qualified technicians. This will usually necessitate contracting external assistance.

In some cases regular maintenance can be included in the purchase or lease arrangements associated with the supply of hardware. This practice is often very desirable as it ensures that maintenance is included in the initial budget for the hardware and avoids the risk that funds may not be available for maintenance at a later date.

Maintenance may also be necessary when hardware breaks down or performs below standard. Response arrangements to such non-routine maintenance can also be included in the organisation's overall information technology strategy. Ongoing arrangements with maintenance and repair technicians will allow problems to be dealt with quickly. Prioritizing needs in advance will allow requests for maintenance to be dealt with as quickly as needed, at a pre-set price.

For example, a schedule could be drawn up showing crucial items that must be fixed within an hour of breaking down, other important but less crucial items that must be fixed within 24 hours, and less important items that must be fixed within a week. The cost of these varying levels of service will generally be higher when a faster response is required.

Systems Maintenance

Computer software systems require constant maintenance. Some of the tasks required include:

• Establishing logical file structures and ensuring users are aware of how they are to be used
• Controlling user access to systems
• Obtaining software licences and ensuring that licence conditions are not breached
• Maintaining consistency across various systems to ensure they are compatible and work is not duplicated
• Maintaining network servers and responding to problems as they arise
• Monitoring available system resources, such as disk storage space and system speeds, to ensure that disks do not become over full or that system performance is unacceptable
• Responding to requests for assistance from users
• Managing interfaces with other systems, such as internet, email and intranets
• Identifying and repairing bugs or faults in software
• Upgrading software as necessary
• Providing, monitoring and upgrading security measures such as virus protection, encryption, firewalls and hacker prevention

Maintaining Information

Computerised information, particularly data and computer programs, must also be maintained to ensure that problems do not arise and that data is available for users when they need it.

Data backup

It is generally accepted that data should be regularly backed up at least once each working day, or even 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, including removable disks of various kinds, multiple hard disks, or magnetic tapes.

The organisation's overall information technology strategy could 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 can also be undertaken to ensure that computer error does not also cause problems.

Live data can also 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 rather than the same server 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 they are available to reload if the production versions of the programs are lost or corrupted. Most programs come loaded on disks (although increasingly programs can be downloaded from the internet, in which case backup copies should be stored locally as there is no guarantee that the same programs will be available in future). Program disks can be stored in a data library and be managed by a responsible officer or staff unit. If needed, program disks can then be easily found and used to correct problems.

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.

Data security measures

Another aspect of maintaining data is keeping it secure. Computer systems can be protected by security systems to ensure that only authorised users have access to them.