If you are running a vCloud Director environment, host maintenance and host management is a bit different. Changes you make in vCenter might not reflect correctly inside vCloud. If vCloud Director does not know about certain changes, the stability and performance of your environment is at risk.
As an example, just adding a new host to the vCloud cluster will not enable it to take on load and to host vApps/VMs. To participate inside the vCloud Director environment the host needs to run a special host agent and that needs to be deployed through the vCloud Director web interface. Another example is host maintenance. You cannot simply put a host into maintenance mode through the vCenter client. If you would do so, vCloud Director would not know that you do and things get messed up pretty quickly.
To put a host into maintenance mode you will need to complete a couple of steps. Inside vCloud Director you will need to go to “Manage & Monitor” | “vSphere Resources” | “Hosts”. This will show you a list of available vSphere hosts for vCloud. Right Click onto the host in question and select “Disable Host”. Inside the vCenter client you can now see that vApps are being evacuated from the host. However, a second step is needed to move all VMs off as well. Wait until the migrations from the step before are completed. Then right click onto the host again and select “Redeploy all VMs”. This will initiate another round of migrations and the a little bit later the host should be completely evacuated. The third step in this area is to put the host into maintenance mode inside the vCenter client. If you experience problems and VMs or vApps are not moving off, you can right click on the host again and select “Unprepare Host” to get the vCloud Director agent uninstalled from the server.
Adding a new host to the vCloud Director environment
Build the host and add it to the cluster that serves resources for the vCloud Director environment. Log into the vCloud Director admin web interface and navigate to “Manage & Monitor” | “vSphere Resources” | “Hosts”. Here you will see a list of your vSphere hosts. The new host should show up already, but is not enable and will also show it is not available or ready. However, if configured correctly it will show green check marks for “VCD Network Isolation Capable”.
Now right click on the host and select “Prepare Host”. This will install the agent for vCloud Director to the host. If all goes well, everything should turn green for this host. Depending on your DRS settings and overall load vCloud Director / vCenter will move VMs and vApps as needed.