What does 'vMotion' require for proper functioning?

vMotion is a critical feature in VMware that allows you to migrate a running virtual machine from one physical host to another with no downtime. The requirement for shared storage between the source and destination hosts is essential for vMotion to work correctly.

When both the source and destination ESXi hosts have access to the same shared storage, the virtual machine's files remain accessible during the migration, allowing for the seamless transfer of the running state of the VM. This ensures that the virtual machine can continue to operate without interruption, as the storage does not have to be copied over during the migration process; instead, the VM's active state can be moved while it's still running.

Properly configured shared storage solutions, such as NAS or SAN, enable this capability by allowing multiple hosts to connect to the same logical storage volume. This eliminates potential issues that could arise from trying to move the virtual machine's storage between hosts during the migration process.

Other factors, such as networking and IP configurations, can impact the environment's overall efficiency and performance, but they are not strictly required to enable the core functionality of vMotion itself. Thus, shared storage is the fundamental requirement that ensures vMotion operates effectively and without interruption.