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Minimum number of Servers needed for an SQL Availability Group RRS feed

  • Question

  • I have looked and I cannot find a definitive answer on this.  What is the minimum number of SQL servers required to create an always on availability group?

    We would like to create an Availability Group with two SQL servers with a file share witness on a third server like we have with Exchange but I can find nowhere that specifically says if this is possible or not.

    Any help would be appreciated.

    Tuesday, January 27, 2015 2:28 PM

Answers

  • Hello,

    You need a minimum of two servers to create an AlwaysOn Availability Group, with two availability replica. The two nodes must be part of a Windows Server failover cluster.

    The following article may be useful.

    https://technet.microsoft.com/en-us/library/ff878487.aspx



    Hope this helps.

    Regards,

    Alberto Morillo
    SQLCoffee.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:12 PM
  • Two windows node with file share witness will allow you to create AO.

    Please read here for more information.


    Regards,
    Vishal Patel
    Blog: http://vspatel.co.uk
    Site: http://lehrity.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:13 PM
  • Yes you can create availability groups with two servers. One Primary Replica and One Secondary Replica is all what is needed.

    " Two types of availability replicas exist: a single primary replica. which hosts the primary databases, and one to eight secondary replicas, each of which hosts a set of secondary databases and serves as a potential failover targets for the availability group"

    https://msdn.microsoft.com/en-us/library/ff877884.aspx


    Regards, Ashwin Menon My Blog - http:\\sqllearnings.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:13 PM

All replies

  • Hello,

    You need a minimum of two servers to create an AlwaysOn Availability Group, with two availability replica. The two nodes must be part of a Windows Server failover cluster.

    The following article may be useful.

    https://technet.microsoft.com/en-us/library/ff878487.aspx



    Hope this helps.

    Regards,

    Alberto Morillo
    SQLCoffee.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:12 PM
  • Two windows node with file share witness will allow you to create AO.

    Please read here for more information.


    Regards,
    Vishal Patel
    Blog: http://vspatel.co.uk
    Site: http://lehrity.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:13 PM
  • Yes you can create availability groups with two servers. One Primary Replica and One Secondary Replica is all what is needed.

    " Two types of availability replicas exist: a single primary replica. which hosts the primary databases, and one to eight secondary replicas, each of which hosts a set of secondary databases and serves as a potential failover targets for the availability group"

    https://msdn.microsoft.com/en-us/library/ff877884.aspx


    Regards, Ashwin Menon My Blog - http:\\sqllearnings.com

    • Marked as answer by Joe Feenin Tuesday, January 27, 2015 3:34 PM
    Tuesday, January 27, 2015 3:13 PM