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Planned and preventative maintenance



All IT components should be subject to a planned maintenance strategy. The frequency and levels of maintenance required varies from component to component, taking into account the technologies involved, criticality and the potential business benefits that may be introduced. Planned maintenance activities enable the IT support organization to provide:

  • Preventative maintenance to avoid failures
  • Planned software or hardware upgrades to provide new functionality or additional capacity
  • Business requested changes to the business applications
  • Implementation of new technology and functionality for exploitation by the business.

The requirement for planned downtime clearly influences the level of availability that can be delivered for an IT service, particularly those that have stringent availability requirements. In determining the availability requirements for a new or enhanced IT service, the amount of downtime and the resultant loss of income required for planned maintenance may not be acceptable to the business. This is becoming a growing issue in the area of 24 x 7 Service Operation. In these instances, it is essential that continuous operation is a core design feature to enable maintenance activity to be performed without impacting the availability of IT services.

Where the required service hours for IT services are less than 24 hours per day and/or seven days per week, it is likely that the majority of planned maintenance can be accommodated without impacting IT service availability. However, where the business needs IT services available on a 24-hour and seven-day basis, Availability Management needs to determine the most effective approach in balancing the requirements for planned maintenance against the loss of service to the business. Unless mechanisms exist to allow continuous operation, scheduled downtime for planned maintenance is essential if high levels of availability are to be achieved and sustained. For all IT services, there should logically be a ‘low-impact’ period for the implementation of maintenance. Once the requirements for managing scheduled maintenance have been defined and agreed, these should be documented as a minimum in:

  • SLAs
  • OLAs
  • Underpinning contracts
  • Change Management schedules
  • Release Deployment Management schedules.

Availability Management should ensure that building in preventative maintenance is one of the prime design considerations for a ‘24 x 7’ IT service.

The most appropriate time to schedule planned downtime is clearly when the impact on the business and its customers is least. This information should be provided initially by the business when determining the availability requirements. For an existing IT service, or once the new service has been established, monitoring of business and customer transactions helps establish the hours when IT service usage is at its lowest. This should determine the most appropriate time for the component(s) to be removed for planned maintenance activity.



To accommodate the individual component requirements for planned downtime while balancing the IT service availability requirements of the business provides an opportunity to consider scheduling planned maintenance to multiple components concurrently. The benefit of this approach is that the number of service disruptions required to meet the maintenance requirements is reduced. While this approach has benefits, there are potential risks that need to be assessed. For example:

  • The capability of the IT support organization to coordinate the concurrent implementation of a high number of changes
  • The ability to perform effective problem determination where the IT service is impacted after the completion of multiple changes
  • The impact of change dependency across multiple components where back-out of a failed change requires multiple changes to be removed.

The effective management of planned downtime is an important contribution in meeting the required levels of availability for an IT service. Where planned downtime is required on a cyclic basis to an IT component(s), the time that the component is unavailable to enable the planned maintenance activity to be undertaken should be defined and agreed with the internal or external supplier. This becomes a stated objective that can be formalized, measured and reported. All planned maintenance should be scheduled, managed and controlled to ensure that the individual objectives and time slots are not exceeded and to ensure that activities are coordinated with all other schedules of activity to minimize clashes and conflict (e.g. change and release schedules, testing schedules.) In addition they provide an early warning during the maintenance activity of the time allocated to the planned outage duration being breached. This can enable an early decision to be made on whether the activity is allowed to complete with the potential to further impact service or to abort the activity and instigate the back-out plan. Planned downtime and performance against the stated objectives for each component should be recorded and used in service reporting.





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