vRA deployments fail after enabling Provisioning on vMotion VMKernel Port in vSphere 8.0 U3

Products

• VMware vSphere ESXi

Issue/Introduction

After the release of Unified Data Transport (UDT) in vSphere 8.0 U3, many customers enable the Provisioning service on vMotion VMkernel ports to accelerate hot- and cold-vMotions, especially when moving VMs across different datastore types (i.e. vSAN <-> VMFS).

In a mixed‑subnet environment this setting can cause vRA (vRealize Automation) deployments to fail with:

• Error from vCenter:  Cannot connect to host

Further investigation into the ESXi hostd.log shows the following error:

• LLPM: transient VM creation failed for <path>.vmx : Cannot open file "...": No such file or directory.

The failure is reproducible when the source and destination clusters have vMotion VMKs on different subnets that are not routable.

Environment

VMware vSphere ESXi

Cause

The Provisioning service (part of UDT) attempts to copy the VM’s files over the VMkernel network that the provisioning VMK is bound to. When that VMK resides on a vMotion port group that is not routable, the host cannot reach the datastore on the destination cluster, so the copy fails and the VM creation is aborted.

Enabling Provisioning on a VMK does not automatically make that VMK routable. UDT does not fall back to the default TCP/IP stack; it uses the VMK’s own network stack.

Resolution

Resolution Options:

1. Use the Management VMK for provisioning (keep Provisioning enabled on the Management VMK)

   • The Management VMK already has a gateway and is routable across all clusters.

   • Pros: No additional network changes; works with existing routing.

   • Cons: Management traffic shares the same NICs – may increase load on the management network.

2. Add a gateway to each vMotion VMK (or configure a routed vMotion port group)

   • Give the vMotion VMKs an IP address with an override of default gateway (or static routes) so they become routable.

   • Pros: Keeps provisioning traffic on the vMotion network, preserving the “fast” path.

   • Cons: Requires changes to the physical network (router/VLAN) and may violate design guidelines that keep vMotion isolated.

3. Create a dedicated Provisioning VMK on a routed VLAN

   1. Create a new VMkernel adapter on a routed VLAN (same VLAN as Management or a separate VLAN with a gateway).

   2. Enable Provisioning on this VMK only.

   3. Disable Provisioning on the vMotion VMKs.

      • Pros: Isolates provisioning traffic, avoids over‑loading Management, and satisfies UDT routing requirement.

      • Cons: Requires an extra VMkernel NIC and a routed VLAN (or a dedicated router).

Additional Information

Additional notes

• Do not enable Provisioning on a VMK that resides on an isolated (non‑routable) vMotion port group.
• After any network change, always validate with vmkping from each host to every other host using the Provisioning VMK.
• If you must keep the vMotion VMKs isolated, disable Provisioning on them and rely on the Management or a dedicated Provisioning VMK.