Had a very strange issue last night with one of my ESXi 4.1 Update 2 hosts. In Vcenter, suddenly one of my hosts showed disconnected. I could ping the host and remote into all virtual machines on the disconnected host, but for some reason Vcenter couldn’t see it. Here were the troubleshooting steps I took yesterday.
1. I used putty to SSH into the disconnected host. I then restarted the service using the command “services.sh restart “.
2. I still could not connect the host in Vcenter. I then tried removing the host and re-adding to Vcenter. It threw an error and would not add.
3. I remoted into my Vcenter VM and tried pinging the disconnected host. The Vcenter server was unable to ping either by name or IP. What was strange is that I could ping another server at that location. If I remoted into any other machine, it could ping the disconnected host…it was only the Vcenter server that couldn’t see it. This was not dns or IP. I restarted the Vcenter server to no avail.
4. Luckily this disconnected host was on site and I was able to connect a monitor and keyboard to it. Normally I would remote in using the ILO port, but that is not configured right now (another story altogether). I restarted the management agents from here. I was now able to ping from the host and from the Vcenter server. YAY!
I don’t know why restarting the management agents from the console was any different that when I SSHed into the machine, but it was.
Favoritevmguy 