vSAN Health Service - No disk claimed on witness host

Products

• VMware vSAN

Issue/Introduction

Symptoms:

The "No disk claimed on witness host" check in the vSAN Health Service verifies that the witness host has claimed a disk group. If this health check is not green (OK), the vSAN stretched cluster has configuration errors that affect its operation and might impact data availability if another site failure occurs.

If the witness host does not have any disk claimed, its fault domain is not available and vSAN cannot provision any objects with Number of Failures To Tolerate set to 1 (FTT = 1). The object creation may work in few scenarios where the stretched cluster has no primary failures to tolerate defined and if the policy has Force Provisioning enabled.

Environment

VMware vSAN 7.0.x
VMware vSAN 8.0.x

Resolution

To prevent or resolve the error state, add a disk group to the witness host.

 

Via vSphere Client

You can use the vSphere Web Client to configure a disk group for the witness host.

1. Navigate to the vSAN cluster.

2. Click the Configure tab.

3. Under vSAN, click Disk Management, select a host from the table, and click VIEW DISKS.

4. Click CREATE DISK GROUP.

1. Select disks to claim.

2. Select the flash device to use for the cache tier.

5. Select the disks to use for the capacity tier.

6. Click Create to confirm your selections.

Refer: Create a Disk Group on a vSAN Host

 

Via CLI

To create the disk group via CLI, you can use the following command

# esxcli vsan storage add -s <cache ID> -d <capacity ID>

To identify these IDs, run the command 

# esxcli storage core device list 

(In the witness, the storage device IDs usually appears as "mpx.hba0:C0:T0:L0")

Example:

# esxcli vsan storage add -s mpx.hba0:C0:T0:L0 -d mpx.hba0:C0:T1:L0