ESXi Host fails to enter Maintenance Mode due to inaccessible datastore during vMotion

Products

• VMware vSphere ESXi
• VMware vCenter Server 8.0

Issue/Introduction

• An ESXi host is unable to enter maintenance mode, with the task stalling at a specific percentage (23%).
• Virtual machines (VMs) remaining on the host fail to migrate to other cluster members.
• The vCenter Server reports the following error:
  Failed to migrate some VMs due to storage issues in datastore <datastore name>, DRS will retry migrating VMs. In a DRS cluster check the Faults page on the DRS tab for troubleshooting.
• Manual vMotion attempts may fail with indications that the virtual machine files (.vmx or .vmdk) are inaccessible on the target hosts, or it can list only the source host in the list of compatible hosts available for migration. 

Environment

vCenter 8.x
ESXi 8.x 

Cause

This issue is caused by a storage presentation mismatch where a datastore containing VM files is not presented to all hosts within the cluster. In a standard vMotion operation, the source and destination hosts must share access to the same datastores. If the destination host lacks access to the datastore, the virtual machine files become unreachable, preventing migration and stalling the host's evacuation process

Resolution

To resolve this issue, ensure consistent storage visibility across the cluster

1. Grant Storage Access:
   Ensure the affected datastores are presented to all the ESXi hosts in the cluster.
2. Verify Mounting:
   In the vSphere Client, navigate to the Storage view and verify that the datastore status is "Normal" and accessible across all cluster nodes.
3. Complete Migration:
   Retry the maintenance mode task or manually vMotion the remaining VMs. Once storage access is uniform, the migration should complete successfully.

Additional Information

Unable to migrate VMs from one ESXi host to another ESXi host