Unable to disable vSAN RDMA support in vSphere GUI after disabling RDMA driver on host

Products

• VMware vSAN

Issue/Introduction

After enabling RDMA support for vSAN, the driver is disabled on a single host to revert all hosts back to TCP. 

When trying to disable RDMA on the cluster setting the option to click  'apply' is greyed out

Environment

VMware vSAN

Cause

This happens due to a host being unable to support RDMA, which blocks configuration whether enabling or disabling it. 

Resolution

Workaround: 

1. SSH into each host on the cluster and run the following command:

esxcfg-advcfg -s 1 /VSAN/IgnoreClusterMemberListupdates

This will ensure the vSAN cluster stays intact without RDMA being re-enabled and causing potential issues. 

2. Right click the host showing issues in the RDMA configuration window and click 'disconnect' 

3. Once host is disconnected, you can then disable RDMA in the GUI without 'Apply' being greyed out.

4. Undo command from step one by running the following command:

esxcfg-advcfg -s 0 /VSAN/IgnoreClusterMemberListupdates

5. Right click the disconnected host and click 'connect'