While looking for a VM on a production vCenter Server instance the other day, I noticed that an ESX host had a red exclamation point on it. I suspected that VMware HA would need to be reconfigured on this host as I have seen this happen from time to time. Upon selecting the ESX host I received the following error message:
Unable to apply DRS resource settings on host (Reason: The name ‘<resource_pool>’ already exists.). This can significantly reduce the effectiveness of DRS.
I have to admit this was the first time I have ever seen this error message. In addition, upon thinking about what the error message actually meant, I did not understand how this problem could occur. At first, I tried to rename the resource pool in question, but the error message just changed to reflect the new resource pool name I had assigned. I did not want to disable and enable DRS as this would remove all the resource pools I had configured.
Any idea how to fix the issue?
Answer: put the host in maintenance mode and, you guessed it, restart the management services. Once the ESX host reconnected, the error and the red exclamation disappeared. This is yet another case where there was a disconnect between the ESX hosts and vCenter Server instance.
© 2010, Steve Flanders. All rights reserved.