A failover (from the English failover for " failover ") is the unplanned change between two or more network services (abstracted functions that are provided by a computer network to the users or participating devices) in the event of a one-sided failure. As a result, the services can be kept highly available despite the failure of one of the systems .
In this way, business-critical applications such as databases , web servers or e-mail can continue to be made available even if a computer fails, since the second system takes over the tasks of the primary system in the event of a failure.
Both servers usually monitor each other with a heartbeat .
Since a deliberate transfer of services from one cluster node to another cannot be referred to as an error (failover), this process is also known as switchover .
A failover cluster or active / passive cluster is a network of at least two computers ( cluster ) in which a second computer takes over its tasks if one computer fails.
The active system is the primary system , the waiting passive systems are the backup or standby systems .
Cluster manager software or a load balancer must be used so that failover can take place automatically and without the intervention of an administrator .
Another advantage of a failover cluster is the possibility of deliberately taking a system out of operation for maintenance purposes, whereby the redundancy is no longer given in a 2-server cluster during this period.
- ↑ Heise: Glossary Failover. Retrieved September 7, 2018 .
- ↑ Techtarget definition: failover. Retrieved September 7, 2018 .
- ↑ Heartbeat, failover and quorum in a Windows or Linux cluster. Retrieved September 7, 2018 .
- ↑ Set up a failover cluster. Retrieved September 7, 2018 .
- ↑ Difference between failover and switchover. January 27, 2010, accessed September 7, 2018 .
- ↑ Failover Cluster. Retrieved September 7, 2018 .
- ↑ IT knowledge: failover cluster. April 10, 2017, accessed September 7, 2018 .