Failover: Difference between revisions
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DarrylBrown (talk | contribs) m Added information relating to an early server failover configuration that was in production in the early 1990's |
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At server level, failover automation usually uses a "[[Heartbeat (program)|heartbeat]]" cable that connects two servers. As long as a regular "pulse" or "heartbeat" continues between the main server and the second server, the second server will not initiate its systems. There may also be a third "spare parts" server that has running spare components for "hot" switching to prevent downtime. The second server takes over the work of the first as soon as it detects an alteration in the "heartbeat" of the first machine. Some systems have the ability to send a notification of failover. |
At server level, failover automation usually uses a "[[Heartbeat (program)|heartbeat]]" cable that connects two servers. As long as a regular "pulse" or "heartbeat" continues between the main server and the second server, the second server will not initiate its systems. There may also be a third "spare parts" server that has running spare components for "hot" switching to prevent downtime. The second server takes over the work of the first as soon as it detects an alteration in the "heartbeat" of the first machine. Some systems have the ability to send a notification of failover. |
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In 1992 in coordination with Distributed Processing Technology and Black Box Cables; Darryl Brown developed a Failover PC Server configuration that allowed for the failover of mirrored or RAID 1 drive sub systems actively connected to two servers. The configuration allowed a production server to failover, within minutes when a server hardware failure, by manually switching to the spare server with a flip of a switch. |
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Some systems, intentionally, do not failover entirely automatically, but require human intervention. This "automated with manual approval" configuration runs automatically once a human has approved the failover. |
Some systems, intentionally, do not failover entirely automatically, but require human intervention. This "automated with manual approval" configuration runs automatically once a human has approved the failover. |
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Revision as of 15:54, 10 August 2013
In computing, failover is switching to a redundant or standby computer server, system, hardware component or network upon the failure or abnormal termination of the previously active application,[1] server, system, hardware component, or network. Failover and switchover are essentially the same operation, except that failover is automatic and usually operates without warning, while switchover requires human intervention.
Systems designers usually provide failover capability in servers, systems or networks requiring continuous availability -the used term is High Availability- and a high degree of reliability.
At server level, failover automation usually uses a "heartbeat" cable that connects two servers. As long as a regular "pulse" or "heartbeat" continues between the main server and the second server, the second server will not initiate its systems. There may also be a third "spare parts" server that has running spare components for "hot" switching to prevent downtime. The second server takes over the work of the first as soon as it detects an alteration in the "heartbeat" of the first machine. Some systems have the ability to send a notification of failover.
In 1992 in coordination with Distributed Processing Technology and Black Box Cables; Darryl Brown developed a Failover PC Server configuration that allowed for the failover of mirrored or RAID 1 drive sub systems actively connected to two servers. The configuration allowed a production server to failover, within minutes when a server hardware failure, by manually switching to the spare server with a flip of a switch.
Some systems, intentionally, do not failover entirely automatically, but require human intervention. This "automated with manual approval" configuration runs automatically once a human has approved the failover.
Failback is the process of restoring a system, component, or service in a state of failover back to its original state (before failure).
The use of virtualization software has allowed failover practices to become less reliant on physical hardware; see also teleportation (virtualization)
See also
- Data reliability
- Disaster recovery
- Fault-tolerance
- Fencing (computing)
- High-availability cluster
- Load balancing
- Log shipping
- Safety engineering
- teleportation (virtualization)
References
- ^
For application-level failover, see for example Jayaswal, Kailash (2005). "27". Administering Data Centers: Servers, Storage, And Voice Over IP. Wiley-India. p. 364. ISBN 978-81-265-0688-0. Retrieved 2009-08-07.
Although it is impossible to prevent some data loss during an application failover, certain steps can [...] minimize it.
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