Long processing times when extending or enabling MON on HCX segments with a large number of VMs

Products

• VMware HCX

Issue/Introduction

When performing Network Extension operations such as unextending, extending, or enabling MON on a segment with a large number of virtual machines (for example, over 400 VMs), the process may take considerable time to complete. Since these operations can last several hours, they may appear to be "stuck" in the user interface, even though they are still actively processing.

Cause

This is expected behavior. For every virtual machine on the segment, the HCX Manager must individually apply configuration changes on both the Network Extension appliance and the NSX side.
Processing a high volume of VMs (for example, 700+ VMs) sequentially requires a considerable amount of time, often exceeding 2-3 hours.

Resolution

In most cases, the operation is functioning correctly in the background and should be allowed to run to completion.
Follow the monitoring steps below to verify activity.

To confirm the task is actively processing VMs and not hung, check the logs on the HCX Cloud Manager:

1. Log in to the HCX Cloud Manager via SSH as the admin user.
2. Navigate to the log directory:
   

   cd /common/logs/admin

3. Monitor real-time progress: Use tail -f to see each VM as it is successfully configured:
   

   tail -f app.log | grep "Successfully set taskInfo for vm" | awk '{print $1,$2,$23,$24,$25}'

4. Check total processed count: Run this command to see how many VMs have been completed so far.
   

   grep "Successfully set taskInfo for vm" app.log | wc -l

Additional Information

If you are enabling MON for segments with more than 400 VMs, you need to scale up the HCX Cloud Manager once the task is completed.
For more details, please access:
HCX Mobility Optimized Networking (MON) Scalability Guide