Disabling UDT (Universal Data Transport)

Products

• VMware vSphere ESXi

Issue/Introduction

This KB gives you options to disable UDT, in case you experience issues, mainly meant as a workaround while troubleshooting the issue. Consequentially related file transports will not use port 8000/TCP anymore and different concurrency configs will apply.

Environment

vSphere 8.0

Cause

UDT is automatically activated when using a provisioning network (VMK with provisioning active). 

Resolution

A return to the classic NFC may be required to get a proper solution in place, e.g. but not limited to these:

• firewall related change-requests that need time for implementation
• configuration issues with the budgeting of file transports

There are several ways to get UDT disabled:

Option 1: Disable the provisioning-VMK.

vSphere will automatically return to classic NFC. Regrettably this will also void the advantages that a separate provisioning network might offer.

Option 2: Disable the use of UDT in vCenter

... using a vSphere advanced config statement in vCenter. Set "config.nfc.disableNfcStreamingOverVmkernel" to TRUE.

Option 3: Configure the VM accordingly

If disabling UDT for specific payloads is needed (for testing, e.g.), a config directive:  Set "nfc.sovDisabled" to TRUE in the configuration file of the VM, rsp. of the template (see below!).

Additional Information

• Configuring advanced settings in the vCenter.
• Configure advanced settings per VM
• UDT is often referred to as NFC-SOV (Network File Copy - Streaming Over Vmotion)