How Availability Services work
Two servers are linked via a virtualization platform that pairs protected virtual machines together to create a single operating environment. We call this technology everRun Availability Services. In fault-tolerant mode, if one physical machine should fail, the application will continue to run on the other physical machine without any interruptions or data loss. In high availability mode, one machine is active, the other is on standby. If one machine fails, the application restarts on the standby machine with minimal interruptions or data loss. In both fault-tolerant and high availability mode, if a hardware component fails, everRun substitutes the healthy component from the second system until the failed component is repaired or replaced.
The I/O is automatically mirrored to the redundant server. This “statepointing” ensures all in-flight transactions as well as data in memory and cache is preserved — without machine restarts or data loss when run in fault-tolerant mode.
We build an operating environment utilizing KVM on one server. Then, we add our Stratus Availability Extensions to create the fault-tolerant environment. Once built, an availability link is used to duplicate and continuously communicate with the 2nd server.