HA Failure on one host "No Active Primaries Found"
I've read the articules on this site concerning this issue, now I'm having the same issue.
I have two ESX 3.5 installs non-production. I can vmotion fine, ping both servers from the other, I can reinstall and make the other server the primary HA sever, but the second server will always give me "No active primiaries found".
Fixed the problem. The issue was DNS on the Vitrualcenter. Once I readded the hosts using their name and not the IP address I realized that maybe the VC couldn't resolve the ESX server names. Why HA didn't like using the IP addresses, I'm not sure.
HA and DRS are heavily dependent on name resolution, whether that comes from DNS or the hosts files on those servers. What happens is that VC will connect VIA the IP address, and then the return will try to come back using the hostname that the ESX server knows it is, which will not match.
Hope that clears it a bit, but resolution is VERY important in VI.