VM Backup fails from Specific Host due to missing datastore

Products

• VMware vSphere ESXi

Issue/Introduction

Veeam backup appliance reports backup failure

Environment

vSphere ESXi 7.x

vSphere ESXi 8.x

Cause

Datastore Unavailable: Not Mounted or Missing from ESXi Host

Resolution

Resolution:

To resolve the issue, ensure that the missing datastore—hosting the virtual machine—is mounted or rescanned on the isolated ESXi host.

• Steps to Mount the Datastore:

1. 1. Log in to the vSphere Client.

   2. Navigate to Storage and locate the required datastore.

   3. Right-click on the datastore and choose one of the following options (based on the datastore type):

      • Mount Datastore

      • Mount Datastore on Additional Hosts

   4. In the prompt, select the ESXi host(s) that need access to the datastore, then click OK.

• To Verify Datastore Access:

1. 1. Select the datastore in the vSphere Client.

   2. Click on the Hosts tab to view a list of all ESXi hosts that currently have access to the datastore.

Note: If mounting the datastore fails with the error: "The name 'Datastore' already exists"
- This indicates that the datastore is already mounted on the ESXi host but is not visible in the vSphere Client UI or inventory.
- In such cases, perform a rescan of the storage adapters at the host level to refresh the datastore visibility. Refer to steps in KB- Performing a rescan of the storage on an ESXi host, Once the rescan is complete, verify that the datastore appears in the inventory and then retry the snapshot backup operation.