Unable to delete and/or remove an edge node from the edge cluster as it shows that edge is being used in Logical DHCP

Products

• VMware NSX

Issue/Introduction

• You are trying to delete an edge node and/or removing it from the edge cluster which has no logical routers attached as seen from System >> Fabric >> Nodes >> Edge Transport Nodes but it throws an error stating "Entity PolicyEdgeNode//infra/sites/default/enforcement-points/default/edge-cluster/<UUID of edge node> cannot be deleted as it is being referenced by entity(s): LogicalDhcpServer/<UUID>/ (Error code: 10026)" as in below screenshot
  
  
  
  
  
  
• When validated from T1 gateway/s >> DHCP Configuration, you see that this edge is being referenced as standby edge
  
  
  
  
• You tried to release the edge node in question by powering it OFF and with standby relocation turned ON at the T1 gateway which has the DHCP profile attached to it (the same profile which the error says while removing the edge node from the edge cluster)
  
  
• You have already validated that on the T1 gateway which has the DHCP profile attached >> standby relocation is turned ON, but when checked for DHCP profiles under Networking profiles section, the DHCP profile in question has Standby relocation turned OFF
  
  

Environment

VMware NSX

Cause

T1 gateway and DHCP profiles are independent when it comes to edge allocation and just having standby relocation turned ON on T1 gateway isn't sufficient to release the edge node from the DHCP profile, so it is a requirement to turn ON standby relocation on the DHCP profile and then trigger the standby relocation failover by powering off the edge in question and then proceed for it's removal/deletion.

Resolution

• Navigate to "Networking Profiles > DHCP" configuration.
• Turn ON the "Standby Reallocation" option on the profile in question.
• Power off the Edge in question, without taking down the node into maintenance mode.
• Proceed with deleting/removing the edge node from the cluster.

Additionally, for standby relocation to function successfully, there must be an additional healthy NSX Edge node in the edge cluster.
Note: Since this is a change to DHCP setup on existing configuration, it is recommended to perform the change over maintenance window.