Error: "There are currently 2 usable fault domains. The operation requires 1 more usable fault domains."

Products

• VMware vSAN

Issue/Introduction

Symptoms:

The user cannot apply a default vSAN policy (FTT=1) to a VM. They get the error, "There are currently two usable fault domains. The operation requires 1 more usable fault domain."

Cause

This issue happened because the vSAN cluster is in a partitioned state, and the policy requires the vSAN to be in a healthy state and three fault domains if the user is trying to apply the vSAN default policy with FTT=1.

When the user checks the vSAN skyline health check, they notice the vSAN cluster partition with one or more ESXi hosts in a different partition.

In order to function properly, all vSAN hosts should be able to communicate properly with each other via the vSAN Network.

If all ESXi hosts in the cluster cannot communicate, a vSAN cluster will split into multiple network partitions. For instance, sub-groups of ESXi hosts may be able to communicate with each other, but not with other sub-groups. 

Resolution

The user needs to resolve the cluster partition. After resolving the cluster partition, implementing the vSAN policy would be successful.

For more information on the cluster partition, please check the following knowledge base article.

vSAN Cluster Partition