If your skyline starts to spit out errors such as:
"Could not execute Online health checks."
You will need to do the following:
1. Login to your Skyline appliance via the website at https://<ip_address>/ as 'admin'
2. Under your "VCENTER SERVER" expand the view below.
3. Select VC_HOSTS
4. Click on the "Restart" button.
This will make sure that the service restarts and the status should change to "upload successful"
Once you have done that, go back to your hosts and click the 're-test' button.