downtime

During downtime, users cannot reach a system or complete an important action. An online shop might still open but be effectively unusable if checkout fails. The severity of the interruption depends on the affected function, the number of users and its duration.

What causes downtime?

Downtime can be planned or unplanned. Planned downtime is an announced interruption for maintenance, migration or a deploymentGlossary · In briefdeploymentA deployment is the process of installing and starting a chosen software version in a target environment so it can be tested or used there.Read more. Unplanned downtime can result from a software bug, failed infrastructure, overload or an outage at an external provider.

MonitoringGlossary · In briefmonitoringMonitoring systematically tracks software, infrastructure or processes through measurements and checks. Deviations can trigger alerts so an administrator can investigate.Read more helps detect and investigate interruptions quickly. Redundant components and failoverGlossary · In brieffailoverFailover is the switch from a primary system to a backup system when the primary system fails or stops working correctly.Read more allow a system to switch to another server or service during a failure. A rollbackGlossary · In briefrollbackA rollback reverses a change so software, configuration or data returns to an earlier state. Teams use it when a change causes errors or other unwanted effects.Read more option for releasesGlossary · In briefreleaseA release is an identifiable software version prepared to be made available to users. It brings together one or more checked changes.Read more and regularly tested recovery procedures can also shorten outages.

Downtime and uptime

UptimeGlossary · In briefuptimeUptime is the time during which software, a server or another service is available and usable, usually expressed as a percentage of an agreed measurement period.Read more measures how long a system is available; downtime measures when it is not. Both are often expressed as percentages over an agreed measurement period. For example, 99.9 percent uptime allows roughly 43 minutes of downtime per month, depending on the exact period and agreements.

Organizations do not all measure downtime in the same way. An SLAGlossary · In briefSLASLA stands for service level agreement: an agreement between a customer and provider about the service, its agreed level and how that level is measured.Read more may specify when measurement starts, which components count and whether planned maintenance is excluded. Availability percentages can therefore only be compared properly when the measurement method is known.