One may find that several tasks in the OA task manager stuck in failed state with the following message:
Task name Collect public folders diskspace usage for service #37 Method name collectFoldersDiskUsageHandler on OBJREF:Exchange:0:getMBXService:37 Last execution output Destination host 'EXDAG01.provider.local' (#12), IP '10.16.22.23' : Node #12 is unmanageable.
Checking this node on the OA side will gives a message "Host is not functioning".
In event viewer on the currently active cluster node the following messages can be found.
Event Type: Error Event Source: POA Event ID: 6 ... Description: The description for Event ID ( 6 ) in Source ( POA ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: POA Agent, 1.
In the System log:
Event Type: Error Event Source: ClusSvc Event Category: Failover Mgr Event ID: 1069 ... Description: Cluster resource 'EXDAG01 - PEM Agent' in Resource Group 'EXDAG01' failed. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
There were issues during the cluster failover described in the following technet article in the component MS Failover Cluster internals. OA agent service (pleskd.exe) could not start therefore host is being reported as unmanageable.
The issue can be addressed by the following technet article. Despite being addressed for Windows 2003, the solution is proved to be applicable on Windows 2008.
Following steps are advised to be taken:
cluster resource "EXDAG01 - PEM Agent" /properties cluster resource "EXDAG01 - PEM Agent" /properties PersistentState=0 net stop clussvc net start clussvc cluster resource “EXDAG01 - PEM Agent” /online
Please note, stopping cluster service will result fail of provisioning of new Exchange services. You may need to schedule appropriate maintenance window to perform this actions.