What feature allows for the migration of VMs without downtime?

The feature that enables the migration of virtual machines (VMs) without downtime is vSphere vMotion. This technology allows administrators to move running VMs from one physical server to another with no noticeable impact on the workload or user experience. It does this by transferring the VM's state, memory, and execution context over a network connection, ensuring that the VM remains active and responsive throughout the entire process.

Using vMotion, businesses can perform maintenance on physical hosts, load balance workloads, and optimize resource allocation without incurring downtime, which is critical for maintaining high availability and service levels in a virtualized environment. This capability is especially important in environments where continuous service is required, such as in healthcare applications, financial services, and e-commerce platforms.

In contrast, other features such as vSphere High Availability and Fault Tolerance focus on protecting VMs from failures rather than facilitating live migrations. Enhanced vMotion Compatibility allows vMotion to occur between hosts with different CPU architectures, but it still relies on the core vMotion technology to perform the migration without downtime.