Who moved my PAM?

If your Exchange 2010 deployment utilizes a DAG in two or more Active Directory sites you may have run into situation where the Primary Active Manager (PAM) is unexpectedly located on a DAG node that resides in another site.  The PAM, aka the “cluster group” will shift around as necessary among the members of your DAG for various reasons.  So you ask, “Who moved my PAM?”:

  1. You may have moved it as part of DAG maintenance.
  2. There was problem with the DAG node hosting the PAM, such as errors in the ESE or a storage problem, and the role moved to a server in an alternate site.
  3. A network communications error occurred, affecting the cluster service heartbeat, causing the PAM to move to what it believes is a surviving member of the DAG.

Unfortunately there is no way to add a server preference to the PAM role.  It would be nice to be able to tell the PAM to try and stay on a server at a preferred active directory site.  The only thing that you can do is to block a DAG member from having database copies activated on it with the following command:


[powershell gutter=”False”]
Set-MailboxServer –Identity EX02 -DatabaseCopyAutoActivationPolicy Blocked
[/powershell]

This isn’t much help as it defeats the purpose of redundancy in the DAG.  As long as you are running your multi-site DAG with DAC mode enable, you shouldn’t have a problem with a split brain scenario.  However the PAM does coordinate database activation and is the quorum resource so getting it back to you preferred site is probably something you should strive towards.  It is safe to manually move this role to another DAG member during production hours.  Use the following commands:

[powershell gutter=”False”]
Import-Module FailoverClusters

Move-ClusterGroup -Name <Group Name> -Node <Node Name> -Cluster <Cluster Name>
[/powershell]

Keep an eye on that PAM!

2 thoughts on “Who moved my PAM?

  1. How do I change the DAG Host?
    Have 2 colo’s the Host connection to SRV1 sometimes is lost and DAG ends up being hosted on SRV2. How do I move the host from SRV2 o SRV1?
    Thank you,

  2. Not sure if you are asking about activating the PAM on SRV1 or activating the DAG databases on SRV1. To activate the PAM on SRV1 use the Move-ClusterGroup cmdlet example above. If you want to activate DAG databases on SRV1 and assuming you only have SRV1 and SRV2, use this cmdlet: Move-ActiveMailboxDatabase -Server SRV1 -Confirm:$FALSE

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