SQL Server – Do I Need a Separate IP Address per Subnet for Each Database in a Basic Availability Group?

availability-groupssql serversql-server-2016

I have a pair of SQL Servers running in two different subnets (in AWS if that matters) and a couple of databases that I want to run in a Basic Availability Group.

My understanding is that in SQL Server 2016 Standard I need a separate Availability Group for every database. Also at least in the user interface it looks like an AG Listener can only belong to a single Availability Group.

I get errors when I try to reuse the IP address for another AG listener (i.e. use 10.0.0.1 and 10.0.1.1 for AG listeners LISTENER1 and LISTENER2)

Do I really need to create a separate AG Listener with two unique IP addresses for every AG and thus every database, or is there a way to reuse either the IP addresses or the AG listeners?

Best Answer

Do I really need to create a separate AG Listener with two unique IP addresses >for every AG and thus every database, or is there a way to reuse either the IP >addresses or the AG listeners?

Yes, really, you do.

In fact, you'll need a unique IP address for each listener for each subnet that listener could potentially live in. Why? Well it's not very helpful to have a listener that can't listen. This is true whether Basic AGs are used or not.

Related Solutions

AlwaysOn – Availability Group Listener in a Multi-Subnet Cluster

To flesh out the accepted answer a little bit for anyone looking for code examples and order of operations, I had to:

First create the Availability Group on the primary node
Add a static subnet IP to the AG listener on the primary node.
Connect to the secondary node and JOIN it to the Availability Group
Connect BACK to the secondary node and add the second static subnet IP address (which belongs to the subnet of the secondary node) to the AG listener.

Here is a partial sample of the code showing the steps above (obviously with dummy IPs and node names):

:Connect PrimaryAGInstName

USE [master]

GO

CREATE AVAILABILITY GROUP [PrimaryAGInstName]
WITH (AUTOMATED_BACKUP_PREFERENCE = SECONDARY)
FOR DATABASE [DBName]
REPLICA ON N'PrimaryAGInstName' WITH (ENDPOINT_URL = N'TCP://PrimaryAGInstName.Domain.Info:5022', FAILOVER_MODE = AUTOMATIC, AVAILABILITY_MODE = SYNCHRONOUS_COMMIT, BACKUP_PRIORITY = 50, SECONDARY_ROLE(ALLOW_CONNECTIONS = NO)),
    N'SecondaryAGInstName' WITH (ENDPOINT_URL = N'TCP://SecondaryAGInstName.Domain.Info:5022', FAILOVER_MODE = AUTOMATIC, AVAILABILITY_MODE = SYNCHRONOUS_COMMIT, BACKUP_PRIORITY = 50, SECONDARY_ROLE(ALLOW_CONNECTIONS = NO));

GO

:Connect PrimaryAGInstName

USE [master]

GO

ALTER AVAILABILITY GROUP [PrimaryAGInstName]
ADD LISTENER N'AG_Listener_Name' (
WITH IP
((N'12.345.67.8', N'255.255.248.0')
)
, PORT=1919);

GO

:Connect SecondaryAGInstName

USE [master]

GO

ALTER AVAILABILITY GROUP [PrimaryAGInstName] JOIN;

GO


:Connect PrimaryAGInstName

USE [master]

GO

ALTER AVAILABILITY GROUP [PrimaryAGInstName]
ADD LISTENER N'AG_Listener_Name' (
WITH IP
((N'12.567.89.0', N'255.255.248.0')
)
, PORT=1919);
GO

Sql-server – SQL Server 2014 AG Listener

Creating a listener creates (permissions must allow, otherwise the entry will be made by the network team) a DNS entry, and has a dependency to an IP address. It logically follows that each listener needs its own IP address, because how else will traffic know where to be directed?

See Failover Cluster Manager>[Cluster Name]>Services and applications> [Availability Group name]. Under Server Name section, the listener name is displayed and shows the IP Address underneath, which is reflected as a Dependencies entry if you open the properties of the listener name.

If you find a way around it, I'd sure like to know, because it doesn't make sense to me that it would work. Good luck!

Best Answer

Related Solutions

AlwaysOn – Availability Group Listener in a Multi-Subnet Cluster

Sql-server – SQL Server 2014 AG Listener

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