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Compute High Availability

High availability (HA) is a design approach that ensures a system is always available, even in the event of a failure. HA is achieved by designing in redundancy, which means that if one component fails, another component can take over. This ensures that the system continues to operate without interruption.

Approaches

  • up to date AMIs are critical for rapid fail-over
  • AMIs can be copied to other regions for safety or DR staging
  • Horizontally scalable architecture are preferred because risk can be spread across multiple instances
  • Reserved instances is the only way to guarantee capacity
  • Auto scaling and elastic load balancing are key components of HA
  • Route 53 can be used to route traffic to healthy instances