Which feature helps maintain zero data loss when a VM on an ESXi server fails unexpectedly?

Fault Tolerance is a feature that provides continuous availability for virtual machines by creating a live shadow instance of a VM that runs on a separate ESXi host. This means that if a primary VM experiences a failure, the shadow VM can immediately take over without any loss of data or interruption in service.

Using Fault Tolerance, write operations are processed simultaneously in both the primary and shadow VMs, ensuring that they are always in sync. This capability is critical for applications that require maximum uptime and cannot afford any data loss, such as financial systems or critical databases.

Other features mentioned, while beneficial in their own ways, do not provide the same level of zero data loss as Fault Tolerance. vSphere High Availability, for example, allows for the automated restart of VMs in case of host failure, but there can be gaps during the recovery, leading to potential data loss. Storage vMotion and vMotion are primarily used for the migration of VMs without downtime, but they don't specifically address data loss in the event of a failure. Thus, Fault Tolerance stands out as the solution that ensures zero data loss.