How to recover a Single DAG Mailbox Server Member
Whoa!!! One of my servers in DAG crashed and it’s crashed for good (RIP)… what next???
The steps outlined in this document is a “MUST-MUST HAVE” for all Exchange pro’s as a part of your DR documentation. I can tell you with confidence that you don’t want to wait for a server to crash and then go haywire looking for this. Read and understand every single information outlined here and try to replicate it in a lab if you have any… Let’s get started…!
In case of single server failure there will not be any impact to the production as the DB’s copies will come online on the other member in DAG. We still need the server back to the production so that we can continue providing the agreed DAG infrastructure. The following step will guide the recovery of the single server failure in the Exchange 2010 DAG.
So, I have a 2 member DAG setup and one of them failed. Following are the steps if you want to recover that server. Yes – I know you can add a different server as a member of DAG, but knowing this process won’t hurt.
If Exchange is installed in a location other than the default location, you must use the /TargetDir Setup switch to specify the location of the Exchange program files. If you don’t use the /TargetDir switch, the Exchange program files will be installed in the default location (%programfiles%MicrosoftExchange ServerV14).
To determine the install location, follow these steps:
- Open ADSIEDIT.MSC or LDP.EXE.
- Navigate to the following location: CN=ExServerName,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=ExOrg Name,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=DomainName,CN=Com
- Right-click the Exchange server object, and then click Properties.
- Locate the msExchInstallPath attribute. This attribute stores the current installation path.
Steps of DAG Single server recovery
Clean-up of the crashed server data from Exchange DAG:
Retrieve any replay lag or truncation lag settings for any mailbox database copies.
Get-MailboxDatabase DB1 | Format-List *lag*
Remove any mailbox database copies
Remove the failed server’s configuration from the DAG.
Remove-DatabaseAvailabilityGroupServer -Identity DAG1 -MailboxServer MBX1 ConfigurationOnly
Evict the node from failover cluster- Open the Failover cluster and evict the crashed node from the cluster.
Now proceed with steps below:
- Reset the server’s computer account in Active Directory
- Join the server to the domain with the same name.
- Install IIS.
- Install .net framework 3.51
- Install Office Filter Pack
- Open a Command Prompt window with run as administrator.
Run the exchange setup with the below cmdlet.
When the Setup recovery process is completed. Open the Exchange management shell and run the below cmdlet.
Add-DatabaseAvailabilityGroupServer -Identity DAG1 -MailboxServer MBX1
After the server has been added back to the DAG, reconfigure mailbox database copies using below 3 cmdlets
Add-MailboxDatabaseCopy -Identity <DBName> -MailboxServer <destination mailboxservername> -ReplayLagTime 0.00:01:00 –truncationlagtime 0.00:01:00 -ActivationPreference number
Suspend-MailboxDatabasecopy –identity <DBNamedestinationservername>
Update-MailboxDatabaseCopy -Identity <DBNamedestinationservername> -SourceServer <sourcemailbox server> -DeleteExistingFiles
Note: Wait for the seeding to complete which might take more than 24hrs (depending on the DB)
Prabhat Nigam (Wizkid)
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