Here’s a lesson in checking the basics! I added new ESXi 5 host to a cluster today and spent a good couple of hours troubleshooting the error:
vSphere HA agent for host [Host’s Name] has an error in [Cluster’s Name] in [Datacenter’s Name]: vSphere HA agent cannot be correctly installed or configured
After a few basic checks, migrating the host in and out of the cluster and rebooting, I headed off to google and began troubleshooting.
I rebuilt an ESX host in my HA/DRS cluster today, following my build procedure to configure as per VMware best practices and internal guidelines. When the host was fully configured and up-to-date, I added it to the cluster and enabled HA and DRS. Then I went to generate some DRS recommendations to balance the load an ease off my overstretched host, but no recommendations were made.
I couldn’t manually migrate any VMs either – it was odd, because both hosts were added into the cluster, and could ping and vmkping each other from the console.