vSAN Health Service - Network Health - Hosts disconnected from vCenter Server

Products

VMware vSAN

Issue/Introduction

This article explains the Network Health - Hosts disconnected from vCenter check in the vSAN (formerly known as Virtual SAN) Health Service and provides details on why it might report an error.

Environment

VMware vSAN 6.x
VMware vSAN 8.0.x
VMware vSAN 7.0.x

Resolution

Q: What does the Network Health - Hosts disconnected from vCenter check do?

If an ESXi host that is part of a vSAN cluster is disconnected or not responding from vCenter Server, it can cause operational issues.

This can mean that vSAN is unable to use the capacity or resources available on this ESXi host. It can also mean that the components residing on the disks on this ESXi host are now in an ABSENT state, placing the virtual machines at risk should another failure occur in the cluster. However, because it is disconnected from the vCenter Server, the overall state of this ESXi host is not known.

This checks whether the vCenter Server has an active connection to all the ESXi hosts in the vSphere cluster.

Q: What does it mean when it is in an error state?

If this health check highlights that an ESXi host is not connected, the vCenter Server does not know its state. The ESXi host may be up, and participating in the vSAN cluster, serving data, and playing a critical role in the storage functions of the vSAN cluster.

However, it could also mean that the ESXi host may be down and unavailable. vCenter Server, and hence the vSAN Health check, cannot fully asses the situation as long the host is disconnected.

How does one troubleshoot and fix the error state?

You should immediately check why an ESXi host that is part of the vSAN cluster is no longer connected to the vCenter Server.

One option is to manually try to reconnect the ESXi host to the vCenter Server using the vSphere Web Client. Right-click the disconnected ESXi host and select Connection from the drop-down menu. Then select Connect. Provide the appropriate responses to the connection wizard where required.

If the ESXi host fails to do a manual connect, you can try connecting to the ESXi host using SSH, if it available, to assess its status.

Another option is to connect to the ESXi host console and investigate possible underlying issues. For more information, see Troubleshooting an ESXi host in a "not responding" state.