Monday, January 12, 2015

Considering an Exchange 2013 DAG without AAP? Careful!

Exchange 2013 SP1 can now benefit from a couple of new clustering features in Windows Server 2012 R2, read all about them in the Scott Schnoll's blog post Windows Server 2012 R2 and Database Availability Groups.

My personal favorite is the option create a DAG without a Cluster Administrative Access Point. This feature allows Exchange to use a cluster without an assigned IP address, IP Address or Network Name cluster resources or Computer Name Object. Windows Server 2012 R2 and Exchange 2013 SP1 no longer need those to manage the cluster and are able to talk to the cluster API directly.

A DAG without an AAP reduces the complexity and simplifies DAG management. Everyone who has worked with Exchange 2000/2003 clusters will agree that reducing the complexity can improve the stability and availability of Exchange greatly.

Unfortunately there are many 3rd party solutions which still require the legacy cluster objects, for instance backup software trying to access the database through the DAG CNO. An example of such software is BackupExec 2012-2014:

Symantec states in HOWTO99184   Backing up Exchange data that:

Backup Exec requires an Exchange DAG to be configured with a Cluster Administrator Access Point to facilitate connectivity to the Cluster Name and Cluster IP address.

Symantec NetBackup has a similar issue however can be tricked to talk to a static server by editing the hosts file: Backing up an Exchange 2013 IP less DAG. Another example is NetApp SnapManager which currently does not support a DAG without AAP.

Unfortunately there's no (supported) way to convert your DAG to a DAG with an AAP so you need to destroy and rebuilt your DAG to correct this issue. So check any dependencies carefully before you opt to deploy a DAG without an AAP.


Seandrethegiant said...

Any idea if Veeam backups have any issue, since they operate at the hypervisor level.

Jetze Mellema said...

You're correct, this issue will not impact Veeam Backup and Restore as it does not use the clustering interface to connect with Exchange.

Unknown said...

SnapManager 7.2 for Exchange supports IP less DAG.

Messaging and Collaboration Architect

Unknown said...

SnapManager 7.2 for Exchange supports IP less DAG. SME 7.2 includes support for E2016 as well.