What is the primary function of vSphere Fault Tolerance?

The primary function of vSphere Fault Tolerance is to protect against hardware failure by creating a duplicate virtual machine (VM) that runs simultaneously alongside the original VM. This technology ensures high availability by maintaining a live copy of the VM that can take over instantaneously in the event of a failure of the primary VM. Fault Tolerance leverages a mechanism that allows the secondary VM to remain in sync with the primary VM, ensuring that there is no data loss and that service continuity is maintained. This approach is crucial in environments where uptime is critical, such as in production systems, where even minimal downtime can have significant impacts.

Other functions mentioned, such as ensuring data integrity during migrations, are related to different aspects of virtualization management and do not specifically address the purpose of Fault Tolerance. Controlling network bandwidth usage refers to Quality of Service features rather than protection from hardware failures. Monitoring the performance of virtual machines is a function of performance management tools, which focus on analyzing and optimizing VM operations rather than providing redundancy for fault resilience. Therefore, the correct answer encapsulates the core capability of Fault Tolerance in maintaining availability during hardware issues.