NFC performance is slow resulting in migration taking longer

Products

• VMware vSphere ESX 6.x
• VMware vSphere ESX 7.x

Issue/Introduction

• Cold migrations or migrating virtual machines between different clusters without shared storage are taking a long time. 
• NFC speed is the situation, and there are no other errors
• NFC for provisioning operations, cold migration, and cloning over WAN links takes more time.

Environment

VMware vSphere ESXi

Cause

• NFC is single-threaded - performance will always be limited by this, and you will never move faster than the single thread.
• NFC is encrypted - you can speed up by disabling SSL and improving the speed up to 20%, this comes at the expense of security and might not be an option for most environments.
• NFC is synchronous - we must READ/WRITE/CHECK, then proceed.
• NFC can only do one operation at a time: READ/WRITE/CHECK.
• NFC is latency aware - it will throttle when latency transitions are seen.

Resolution

• The provisioning TCP/IP stack can be enabled and configured on the ESXi host for some additional performance - vSphere TCP/IP Stacks
• You can disable SSL with the KB Disabling SSL for NFC data traffic in vCenter Server
• Avoid using NFC for any deployment or movement of large files where speed is a priority.
• You can use UDT(Unified Data Transport) protocol after you upgrade to vsphere 8 or higher on both side(Source/Target) and activating provisioning service on vmkernel interface.

Additional Information

NFC's performance-limiting factors prevent it from being used to rapidly deploy VMs across non-shared storage.

For UDT(Unitified Data Transport) protocol, please refer to below articles.
vSphere vMotion Unified Data Transport
Extreme Performance Series: vSphere 8 Enhancements for VM Cold Migrations, vMotion, and Cloning