configureing the listener in always on

Question

Hi, Im building a sql 2012  two node always environment for the first time.

There are 2 datacentres A (primary) and B (DR). Both SQL Nodes will be built at A, but there is a Hyper V virtual failover which will copy both nodes to B in the event of a problem.

If I give the listener an IP address at site A will the availability groups be able to failover at site B?

Thanks,

Zoe

Answer 1

It is common scenario that setting  an Always On availability group in a multi-site cluster for disaster recovery (DR) .  two nodes in the cluster at the primary data center with a file share or disk witness, and a third node at a remote data center.

Availability groups and the associated availability group listener support automatic client redirection to the primary replica or redirection to available readable secondaries. Availability group listeners remove the need to designate a failover partner in the client connection string. 

some customers make use of a third data center for deployment. In most cases, the primary reason for such a solution is to provide automatic failover of the availability group between the primary and disaster recovery data centers. One way to achieve this is to deploy the two replicas in these two data centers and a file share witness in the third data center.

Answer 2

This really depends on how the Hyper-V failover is configured. When you say "there is a Hyper V virtual failover which will copy both nodes to B in the event of a problem" do you mean that the SQL Server Availability Group is running on a virtual machine in a Hyper-V cluster and that the virtual machines are being replicated over to the DR site? What else is getting replicated over to the DR site?

An Availability Group Listener Name gets created as an Active Directory Domain Services virtual computer object and a DNS entry with the virtual IP address. How do your domain controllers and DNS servers get replicated over to DR.

Here's a blog post that explains the role of both Active Directory and DNS in an Availability Group

Why Active Directory Domain Services Authentication Matters (Five Things That You Need To Consider When Deploying SQL Server Availability Group Replicas in a Disaster Recovery Site - Part 1)

Much Ado About DNS (Five Things That You Need To Consider When Deploying SQL Server Availability Group Replicas in a Disaster Recovery Site - Part 2)

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Edwin Sarmiento SQL Server MVP | Microsoft Certified Master/Solutions Master
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Answer 3

Hi There,

you are not failing over the data centres. as one data centre goes down you will be bringing the second data centre.

your server guys may be replication the environment so that they can bring the environment up and running.

you are not changing any configuration in second data centre. so you every thing should work when your second data centre is up.

Thanks

kumar