Setting up Always ON Availability Group in Multi Subnet Cluster – Recommendations

While planning to configure always on availability group for first time on a multi subnet cluster found following use articles, it provides clear picture in terms of design and architecture, our requirement was to build SQL 2012 cluster on DC1 along with a reporting standalone SQL instance in same DC1, along with it, we want to have DR solution in DC2 where two standalone SQL instances are present on their respective server, to achieve this configuration following articles helped,


Following article highlights Microsoft instructions on configuring Windows multi subnet cluster for Always ON availability groups,


Below are highlighted important page numbers for easy reference,


Page number 11, this diagram talks about 1 windows cluster in 2 different subnets where the A1 and A2 are in a SQL Failover cluster and rest of the nodes A3, B1, B2 in Standalone. Exactly the same way we want it for our environment. It uses FileShare Witness as optional which is a best practice to have one.



Then refer to Page 15 to 20 to understand how Quorum voting works and how majority decide.


Link for read-only configuration of AlwaysOn can be found here


Detailed ports to be opened:



However, check the article below!/2013/04/windows-server-clustering-sql-server.html this is not a Microsoft article. Infrastructure team can always review and verify if it is correct or if we need to add or remove any from the list.


Hope this helps.

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About the Author: Nitin G

Indian born, trekker, biker, photographer, lover of monsoons. I've been working full time with SQL Server since year 2005 and blogs to post the content aquired during my research on new topics or fixing issues faced by me as a DBA while working in different kind of projects, hope some of my posts may helps others in SQLDBA community. Everything you read on my blog is my own personal opinion and any code is provided "AS-IS" with no warranties!

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