Best Practices for Relocating ESXi Cluster Hosts Between Racks (Non-vSAN)

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

Customers may need to physically relocate an active ESXi cluster (e.g., Cisco UCS or other non-vSAN hardware) from one data center rack to another. The primary requirement is to complete the move without incurring virtual machine (VM) downtime or service outages.

Resolution

Phase 1: Pre-Move Requirements and Verification

Before starting, ensure the new rack is fully prepared to match the existing environment to prevent migration failures.

• Networking Consistency: The new rack’s switches must have identical VLANs, trunking configurations, and MTU settings. Any discrepancy will cause vMotion to fail or VMs to lose connectivity after migration. VMware vSAN Upgrade Best Practices
• Storage Connectivity: Verify that the server hardware (e.g., Cisco UCS Fabric Interconnects or Nexus switches) has paths to the same SAN storage used in the current rack.
• Cluster Capacity: Ensure the cluster has enough compute and memory overhead to run all VMs on N-1 hosts (eg.,6 hosts in a 7-host cluster) while one host is offline.
• DRS Settings: Set vSphere Distributed Resource Scheduler (DRS) to "Fully Automated." This allows vCenter to automatically migrate VMs off a host when entering Maintenance Mode.

Phase 2: Step-by-Step Relocation (The "Rolling Move")

Repeat these steps for each host in the cluster, one at a time, to maintain continuous availability.

1. Enter Maintenance Mode:
• Right-click the host in vCenter and select Maintenance Mode > Enter Maintenance Mode.
• DRS will automatically vMotion all running VMs to the other available hosts.
  Warning: Monitor the migration. If any VM fails to move (e.g., due to a local ISO mount or "must" affinity rules), resolve the conflict manually to avoid downtime.
  
  
2. Verify Host is Clear: Once the host successfully enters Maintenance Mode, ensure no VMs remain running on it.
   
   
3. Power Down and Physical Move:
• Gracefully shut down the ESXi host via vCenter or the CIMC/IPMI interface.
• Physically move the host to the new rack.
• Cable the host (Power, Management, Data, and Storage uplinks).
  
  
4. Power On and Connectivity Check:
• Power on the host.
• Once it boots, verify in vCenter that it shows as "Connected" (it will remain in Maintenance Mode).
  Crucial: Perform a health check on the host’s networking and storage. Ensure all datastores are visible and the vMotion network is reachable.
  
  
5. Exit Maintenance Mode:
• Right-click the host and select Maintenance Mode > Exit Maintenance Mode.
• DRS will begin balancing the cluster by moving VMs back onto this host.
  
  
6. Stabilize: Wait for the cluster to stabilize and for VM performance to level out before proceeding to the next host in the sequence.

Additional Information

For vSAN Environments refer

VMware vSAN Upgrade Best Practices
Moving vSAN Hosts/Nodes from one cluster to another within the same vCenter