How to Unlink vCenter 6.7 from Enhanced Linked Mode

Case: Unlink vCenter 6.7 from linked mode?

If you have multiple vCenter Servers, you may deploy Enhanced Linked Mode to centrally manage them to work simultaneously. vCenter Enhanced Linked Mode (ELM) allows you to log in to any single instance of vCenter Server and view and manage the inventories of all the vCenter Server systems in the group.

However, if one of your vCenter Servers in Linked Mode was dead, removed, or only not in use anymore, you will receive warnings every time you open the master vCenter. Therefore, if you no longer need any of the appliances, you can remove vCenter Server from Linked Mode and delete the appliance from the vSphere inventory and domain.

How to remove vCenter 6.7 from Enhanced Linked Mode

Unlike the Enhanced Linked Mode in vCenter 6.0 and previous versions which requires the external Platform Services Controller (PSC) nodes, starting with vSphere 6.5 Update 2, the Enhanced Linked Mode for vCenter Server Appliance deployments with an embedded PSC is supported and suitable for most deployments. And for vCenter 7 Linked Mode and later, the external PSC deployment model is not supported.

This leaves vCenter Server 6.7 with 2 different Enhanced Linked Mode deployments, the embedded PSC and the external PSC.

• For vCenter 6.7 with an embedded PSC, VMware provide Cross Domain Repoint feature to repoint an embedded node to a new domain to separate the vCenter from the original domain.
• For vCenter 6.7 with an embedded PSC or an external PSC, you can decommission and delete the appliance from the vSphere inventory and domain. However, it is not suggested by VMware to use this method to break ELM/ unlink vCenter Server/ removing from linked mode.

You should choose between them according to your actual needs.

Before you start, please note that the process for removing a vCenter Server or a Platform Services Controller from the vSphere domain is irreversible. After you remove an appliance from the domain, you cannot rejoin it to the same domain. You must perform a re-install or a re-deploy of vCenter Server or Platform Services Controller system in order to re-join it to the domain.

In addition, it is highly recommended that you perform vCenter backup in advance, as all vCenter services will be restarted.

How to unlink vCenter 6.7 with an embedded PSC

1. Shut down the target node that need to be repointed to a different domain. For example, Node C.

2. Decommission the embedded node that is being repointed.

For example, to decommission Node C, log into Node B (on the original domain) and run the following command:

cmsso-util unregister --node-pnid Node_C_FQDN --username Node_B_sso_administrator@sso_domain.com --passwd Node_B_sso_adminuser_password

After unregistering Node C, services are restarted. References to Node C are deleted from Node B and any other nodes that were linked with Node C on the original domain.

3. Power on Node C to begin the repointing process.

4. Run the execute command. In execute mode, the data generated during the pre-check mode is read and imported to the target node. Then, the vCenter Server is repointed to the target domain.

For example, repointing with no replication partner (repointing to a new domain), run the execute command with the following:

cmsso-util domain-repoint -m execute --src-emb-admin Administrator  --dest-domain-name destination_PSC_domain

How to unlink vCenter 6.7 with an external PSC or an external PSC

☞ Pre-requisite: Find and note the PSC that the vCenter Server is currently pointing to by running the command:

• VCSA:

#/usr/lib/vmware-vmafd/bin/vmafd-cli get-ls-location --server-name localhost

• Windows VC:

C:\Program Files\VMware\vCenter Server\vmafdd\vmafd-cli get-ls-location --server-name localhost

Shutdown the Platform Services Controller that you no longer need, and manually re-point all vCenter Servers and all vCenter Server instances registered with the PSC to another PSC within the domain.

☞ vCenter Server Appliance:

1. Log in as root to the appliance shell of one of the Platform Services Controller appliances within the domain.

2. To enable the Bash shell, run the shell.set --enabled true command.

3. Run the shell command to start the Bash shell and log in.

4. Run the cmsso-util unregister command to unregister the stopped PSC:

cmsso-util unregister --node-pnid FQDN_or_IP_address_of_target_PSC --username administrator@your_domain_name --passwd 'vCenter_Single_Sign_On_password'

Note:
1. You must run this command only on one of the PSC replication partners, as the synchronization removes the entries from all other PSC replication partners.
2. There is downtime involved in executing cmsso-util unregister command, it will restart the services on the vCenter Server / PSC where you are executing the command. The same is true for the later steps.

5. Delete the Platform Services Controller appliance that you no longer need from the vSphere inventory.

6. Log in as root to the appliance shell of the Platform Services Controller appliance with which the vCenter Server Appliance is registered.

7. Run the cmsso-util unregister command to unregister the vCenter Server Appliance:

cmsso-util unregister --node-pnid FQDN_or_IP_address_of_the_vCenter_Server_Appliance --username administrator@your_domain_name --passwd 'vCenter_Single_Sign_On_password'

8. Power off and delete the vCenter Server Appliance that you no longer need from the vSphere inventory.

☞ vCenter Server for Windows:

1. In the Platform Service Controller, click Start > Run, type cmd, and click OK. The Command Prompt window opens.

2. Navigate to C:\Program Files\VMware\vCenter Server\bin\.

3. Run the cmsso-util unregister command to unregister the stopped PSC:

cmsso-util unregister --node-pnid FQDN_or_IP_address_of_target_PSC --username administrator@your_domain_name --passwd vCenter_Single_Sign_On_password

4. Delete the Platform Services Controller appliance that you no longer need from the vSphere inventory.

5. Run the cmsso-util unregister command to unregister the vCenter Server:

cmsso-util unregister --node-pnid FQDN_or_IP_address_of_target_vCenter_Server --username administrator@your_domain_name --passwd vCenter_Single_Sign_On_password

6. Power off the vCenter Server.

Summary

If one of your vCenter Servers in Linked Mode was dead, removed, or only not in use anymore, you may receive the “Could not connect to one or more vCenter Server Systems” warnings every time you open the master vCenter. This article showed how to unlink vCenter 6.7 from enhanced Linked Mode with an embedded or external Platform Services Controller.

The process for removing a vCenter Server or a PSC from the vSphere domain is irreversible. You must perform a reinstall or a redeploy of vCenter Server or PSC system in order to rejoin it to the domain. Therefore, before you start, you’d better perform vCenter file-based backup in advance.