The VM Direct Engine (also known as the vProxy) is the virtual appliance responsible for performing data movement during VMware backup and restore operations. While some attributes are 'baked in' during the initial OVF deployment, others are logical configurations that can be adjusted.

Transport Mode: This setting determines how the engine accesses the virtual machine disks (e.g., HotAdd, NBD, or NBDSSL). Administrators can modify the Transport Mode at any time after the engine has been added to PPDM to optimize performance based on the current network or storage environment.

Fixed Deployment Attributes: Attributes such as the Network, Data Store, and the ESXi Host where the appliance is physically located are part of the initial virtual machine deployment parameters in vCenter. If these underlying infrastructure components need to be changed, it typically requires a redeployment of the VM Direct Engine appliance to ensure proper alignment with the vSphere environment.

Other Modifiable Settings: In addition to Transport Mode, administrators can also modify the engine name and the maximum number of concurrent sessions after the engine has been registered.