vSAN Cluster Partition Issue

Products

• VMware vSphere ESXi
• VMware vCenter Server 8.0

Issue/Introduction

Host is showing as in its own cluster in the vCenter UI, which indicates it did not join the existing cluster.

Environment

vCenter 8.0 U3

ESXi 8.0 U3

Cause

The ports needed for vSAN to work correctly were closed after being opened by vSAN when enabled. 

• TDP/UDP 23451 - Reliable Datagram Transport (RDT)
• TCP/UDP 12345 - Clustering Service (CMMDS)
• UDP 13221 - Stretched Cluster / Witness

Resolution

Verify the following ports are open.

• TDP/UDP 23451 - Reliable Datagram Transport (RDT)
• TCP/UDP 12345 - Clustering Service (CMMDS)
• UDP 13221 - Stretched Cluster / Witness

 

Troubleshooting network and TCP/UDP port connectivity issues on Hosts

Use “netcat” (nc) with the following syntax for checking TCP ports on a remote host.

#nc -z <destination IP> <destination Port>

For UDP ports, use this syntax.

#nc -zu <destination IP> <destination Port>

 

You are looking for a response of, “succeeded” after running the commands.