Hi everyone, Andy Nadarewistsch here, and today I want to talk about passive node visibility in System Center Data Protection Manager. To be more specific I would like to discuss why passive nodes would not show in the DPM console. In general, there are only a few reasons why you would not see a passive node or an Exchange DB listed in the DPM console when protecting a DAG:
The agent is not installed on any of the nodes
that owns the Mailbox DB attempting to be protected
There are VSS errors causing the datasources not to enumerate
The EnableVSSWriter regkey is set to 1
Looking at the last scenario we will review how DPM responds when the registry key below exists:
Note the important notice that is given in the article:
Default registry key settings:
After making the change:
DPM is not affected until AFTER the replication service is restarted. What this means is that the registry key change can lay dormant and an Exchange server replication service restart or reboot may trigger abnormal behavior in DPM.
Now let’s see what DPM shows. Going back and re-enumerating the DAG, notice we no longer see DB03. This is because the passive copy was on Node 2 and the active copy was on Node 3 which is not protected by this DPM server or may not protected at all.
However, notice that the Node 2 still shows under DB01 since it holds the active copy.
Now let’s do one final test. I am going to setup Exchange so both the active and passive copies are on nodes protected by this DPM server and the passive copy resides on Node 2. To do this I activated the passive copy for DB01 to Node 1. This switched the active\passive copy configuration.
New Configuration for DB01:
Looking at the DPM console not only is DB03 still gone, Node 2 for DB01 is no longer selectable.
This behavior can be compounded if the Exchange Registry key is on more than one DAG member.
DPM will not see passive copies and\or nodes when the replication writer is disabled. If you find missing components during enumeration please check the following potential causes.
1) The agent is not installed on any of the nodes that owns the mailbox database attempting to be protected. If this is the case, ensure that an agent is installed on the node that holds the Mailbox database you are attempting to protect.
2) The EnableVSSWriter regkey is set to 1 under
If this is the case, check all nodes of the DAG and ensure that the registry does not exist, or if it does, that
is not set to 1. If you make this change, remember to restart the Exchange Replication Service for it to take effect.
3) There are VSS errors causing the datasources not to enumerate. If so, verify that all Exchange Node and Exchange VSS components are functional.
Ensure all databases are mounted and healthy
vssadmin list writers
– Check to see if the Exchange Writer is in stable state