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Last night we received a notification from vCenter saying that it couldn't connect to the agent on one of our hosts, and that the "Host and Power status" was in error and the server was disconnected.

There were no issues with any guests running on the host, so we left it for the morning.

But when checking the task & event and alert logs, we find nothing. The host logs also show no issues at that time.

No reference to anything having gone wrong, nothing to tie that notification back to.

Even if the issue was temporary and fixed itself, should't there be something in the log indicating that some type of trouble occurred?

Also, if it in fact automatically recovered, why didn't vCenter send its usual "Oh hai, everythings fine nao" notification when the system recovered?

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Regarding the alerting for when an alarm clears, you need to alter the Alarm definition so that the notification is triggered on a change of state 'to green' rather than the default, which triggers when the state changes to anything 'from green'. To do this:

  • Open up vSphere Client
  • Select the virtualcenter at the top of the tree
  • Select the 'Alarms' tab'
  • Select 'Definitions'
  • Pick the alarm definition that you want to alter (e.g. 'Host Connection State')
  • Right Click -> edit Settings
  • Switch to the 'Actions' Tab
  • Define alert actions for the last column (state change from Warning to Green)

Here's the column you need to configure: enter image description here

Regarding the disconnections, are you running ESXi or ESX? The logging on ESXi rolls over very quickly (especially messages) so you may not be able to go far back enough to see the disconnection information. If this is the case you can rectify it by configuring the host to log to an external syslog server. We've seen host disconnection issues for strange reasons recently, most notably that a checkpoint appliance between the host and vcenter was interfering with packet order (via it's 'Intelligent' IDS) and causing hosts to regularly drop to an unmanageable state until we restarted the management services. Are there any WAN links or firewalls between the hosts and vcenter?

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Thanks for nice write up. Unfortunately all of the alarms definitions already have a mail notification set for the warning->green state. That's why I'm surprised we didn't receive one. – ryandenki Aug 9 '11 at 3:45
The hosts are all ESX 4.1. I looked at the host log and didn't see any issues around that time, thanks for the tip. This particular ESX host is in the same data center and network segment--I think they are even on the same pair of redundant switches. The Service Console connections are all on a private VLAN visible only to the ESX hosts and vCenter server; there is no IDS or firewall in between. – ryandenki Aug 9 '11 at 3:48
Interesting. Does the timestamp of the error you received match up with the local times of the ESX host and your mail client? I ask in case it was an old alert that got snagged somewhere. – Chris Thorpe Aug 9 '11 at 12:00

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