#High #availability (HA) is the ability of a system or #system component to be continuously operational for a desirably long length of time.
Availability can be measured relative to "100% operational" or "never failing.

How to achieve #high #availability
A highly available system should be able to #quickly recover from any sort of failure state to minimize interruptions for the end user. Best practices for achieving high availability include:
• Eliminate single points of failure or any node that would impact the system as a whole if it becomes dysfunctional.
• Ensure that all systems and data are backed up for simple recovery.
• Use load balancing to distribute the application and network traffic across #servers or other #hardware. A popular example of a #loadbalancer is #HAProxy.
• Continuously monitor the health of #backend servers.
• Distribute resources geographically in case of power outages or natural disasters.
• #Implement reliable crossover or failover In terms of storage, a redundant array of independent disks (RAID) or storage area network (SAN) are common approaches.
• Set up a system that detects failures as soon as they occur.
• Design system parts for high availability and test their functionality before implementation

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