On a dual-node ztC Edge system, Stratus Redundant Linux software provides two user-defined availability levels for VMs: High Availability (HA) and Fault Tolerant (FT).

You select a VM’s protection or availability level when you create or import the VM by using the ztC Edge Console.

Use Fault Tolerant (FT) operation for applications that need the highest levels of availability. In FT operation, an application continues to run without downtime during a fault. The ztC Edge software transparently protects an application by creating a redundant environment for a VM running across two physical machines (PMs). With an identical instance of the selected VM on a second host, the ztC Edge software provides FT-class protection of the VM.

When enabled, FT operation transparently protects a VM from all faults, with no downtime, and FT operation:

• Eliminates downtime due to any CPU, memory, I/O, or other physical machine (PM) failure.

• Handles failures without IT intervention.

• Ensures no data loss.

• Provides continuous, active validation of all components.

• Assures complete redundancy and recovery at all times.

(The supported VM availability levels depend upon the system model, as listed in Virtual Machine Recommendations and Limits.)