Solution availability requirement
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Infrastructure HA
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DR / Failover
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Application HA
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Multi-geo-location application HA
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| Protection from core platform failure – In the event of a failure in the underling systems; storage, networking or compute (hyper-visor). Virtual machines will failover to different hardware and restart. The VM will fail, then restart on a different part of the system.The process results in a period of downtime, users connected to or accessing the applications within the VM will be disconnected. Data loss may occur and no provision for VM start-up order or dependencies is made |
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| Protection from core platform failure or application level failure with a known recovery period and data loss target (RTO and RPO) – – In the event of a failure in the underling systems; storage, networking or compute (hyper-visor). Virtual machines will failover to different hardware and restart. The VM will fail, then restart on a different part of the system.The process results in a period of downtime, users connected to or accessing the applications within the VM will be disconnected. VM (application) recovery and start up is instigated via failover workflow and VM (application start up order and dependencies are observed to guarantee the application is operational within a known / stated and tested period. |
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| Applications and services that can remain operational during underlying system failure or application faults – Using the high-availability and system resilience features built into an application (application specific), services and capabilities remain available to users or recover in a known period of time (RTO). Resilience should provide protection to both underlying system failures and applications level faults.The period of downtime / failover experience will be depend on the application. Failover should be application and dependency aware. |
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Applications and services that can remain operational in the event on total location failure or access loss – Using the high-availability and system resilience features built into an application (application specific), services and capabilities remain available to users or recover in a known period of time (RTO) even in the event of a total failure (either application or underlying system) within an entire geographical location.The period of downtime / failover experience will be depend on the application as with the amount of data loss (if any). Failover should be application and dependency aware.End user reconnection / access may depending on the correct deployment of ancillary capabilities to correctly direct users to the active system. The commonly include one or more of the following:
- DNS changes / multi-target zone files
- Load-balancing
- Connection redirection
- IP failover / targeting via dynamic routing (commonly BGP)
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