Not able to add host due to datastore duplication

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms

• While adding the host from the vSphere UI, receiving below error

• The host was taken out of the cluster for upgrade activity.
• The datastore (DatastoreName) was mounted to the respective host, and even after removing the host from the cluster for the upgrade, the datastore remains present.
• Checked the VM tab and can see 2 VMs are available in the VM list on the datastore.
• Enter SDRS Maintenance task was stuck at 1 % for the respective datastore.

• Found Snapshot available on the 2 VMs which are available on the respective datastore.

Environment

VMware ESXi 7.x 

VMware ESXi 8.x

Cause

The presence of old snapshots referencing the existing datastore prevents it from being automatically unmounted when the host is removed from the cluster.

The snapshots of the affected VMs retained pointers to the old datastore, which caused the datastore to remain in the system and prevented it from entering the SDRS (Storage DRS) maintenance task. As a result, the datastore could not be removed from the inventory.

Resolution

• Identify and delete any old snapshots associated with the VMs that reference the datastore.

• Ensure the datastore is no longer in use by any VMs or hosts.

• After removing the snapshots, proceed with the SDRS maintenance task to properly unmount and remove the datastore from the inventory.

• Add the host back to the cluster and the process will complete successfully.