Browse Definitions :

uptime and downtime

What is uptime and downtime in computing?

In computing, uptime is a measure of how long a computer or service is on and available. Downtime is the measure of how long it is not available. Services measure uptime as a percentage of total time.

What is uptime?

Uptime tells users how long a computer or service has been available. Historically, uptime was mainly a measure of the consecutive time a single computer was powered on before it was rebooted or powered off. This could be shown with the simple uptime command. Some system administrators would take pride in having long uptimes, sometimes measured in years. They might take extreme measures such as avoiding updates or applying patches to a live system.

How the 9s translate to network downtime.
The five nines or 99.999% availability is the gold standard for uptime reliability.

Modern high availability services no longer rely on a single computer to run. Clustered and balanced servers allow for a server to go down without affecting the entire service. Phased rollouts apply patches and updates to groups of servers at a time instead of all servers to allow for some servers to be available while others are restarted.

Service availability is now a better measure of service reliability than just uptime. This is often expressed as a percentage of available time versus unavailable time.

Even 99% is unacceptable for many services. This would translate to roughly three days of downtime each year. Instead, it is measured in the number of "nines" of availability. Five nines -- or 99.999% availability -- is considered the gold standard. This represents only about five minutes of downtime a year.

How to increase uptime

Strategies to increase uptime include the following:

What is downtime?

Downtime tells users how long a service is unavailable. Downtime can be planned due to maintenance or unplanned due to an outage. It is impossible to eliminate downtime, but it is important to try to minimize it. Downtime usually represents lost money due to lost revenue, unhappy customers or lost worker productivity.

Planned and unplanned downtime can be covered differently depending on the service-level agreement.

How to decrease downtime

Strategies to decrease downtime include the following:

Be prepared for planned and unplanned downtime and consider reliability, availability and serviceability when designing, manufacturing, purchasing and using computer products and services. See why network monitoring tools must offer more insights upfront, learn about device reliability engineering and how it promotes product reliability, and explore the Uptime Institute's data center availability tier standards.

This was last updated in June 2023

Continue Reading About uptime and downtime

  • personally identifiable information (PII)

    Personally identifiable information (PII) is any data that could potentially identify a specific individual.

  • zero-day vulnerability

    A zero-day vulnerability is a security loophole in software, hardware or firmware that threat actors exploit before the vendors ...

  • DNS attack

    A DNS attack is an exploit in which an attacker takes advantage of vulnerabilities in the domain name system.

  • data collection

    Data collection is the process of gathering data for use in business decision-making, strategic planning, research and other ...

  • chief trust officer

    A chief trust officer (CTrO) in the IT industry is an executive job title given to the person responsible for building confidence...

  • green IT (green information technology)

    Green IT (green information technology) is the practice of creating and using environmentally sustainable computing resources.

  • diversity, equity and inclusion (DEI)

    Diversity, equity and inclusion is a term used to describe policies and programs that promote the representation and ...

  • ADP Mobile Solutions

    ADP Mobile Solutions is a self-service mobile app that enables employees to access work records such as pay, schedules, timecards...

  • director of employee engagement

    Director of employee engagement is one of the job titles for a human resources (HR) manager who is responsible for an ...

Customer Experience
  • digital marketing

    Digital marketing is the promotion and marketing of goods and services to consumers through digital channels and electronic ...

  • contact center schedule adherence

    Contact center schedule adherence is a standard metric used in business contact centers to determine whether contact center ...

  • customer retention

    Customer retention is a metric that measures customer loyalty, or an organization's ability to retain customers over time.