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migrating server involved in always on high availability RRS feed

  • Question

  • I try to find documentation about migration of servers involved in always on high availability solution.

    What I wonder basically is if we can upgrade the read only instance from 2012 to 2014 and then fail over?  Typically, earlier version of sql server can be restored on later versions but not the oposite.  Is it also true for always on?  Can a sql 2012 server synchronize to a sql 2014 server.

    If so, once you fail over, the replication on opposite direction would probably becomes impossible and require to temporarily remove the 2012 server from always on until it is upgraded and can be added back?

    Anybody with valuable input could comment on the feasibility of this strategy?

    Sunday, October 26, 2014 5:33 PM

Answers

  • Hi Antoine,

    As your post, earlier version of SQL Server can be restored on later versions but not the opposite, it also applies to the SQL Server that involved in AlwaysOn Availability Groups.

    According to my knowledge, it is not recommended that create AlwaysOn Availability Groups between different SQL Server versions. As after upgrading the secondary replica to SQL Server 2014, when AlwaysOn fails over, the secondary replica acts as primary replica. Then once AlwaysOn fails over again, the upgraded primary replica can no longer ship logs to any secondary replica that has not yet been upgraded to SQL Server 2014. Therefore, the best choice is to perform a rolling upgrade for the Availability Group Servers in your scenario.

    For more details, please review the following article.
    Upgrade and Update of Availability Group Servers with Minimal Downtime and Data Loss: http://msdn.microsoft.com/en-us/library/dn178483.aspx


    Thanks,
    Lydia Zhang

    • Marked as answer by Antoine F Monday, October 27, 2014 3:46 PM
    Monday, October 27, 2014 8:12 AM

All replies

  • Hi Antoine,

    As your post, earlier version of SQL Server can be restored on later versions but not the opposite, it also applies to the SQL Server that involved in AlwaysOn Availability Groups.

    According to my knowledge, it is not recommended that create AlwaysOn Availability Groups between different SQL Server versions. As after upgrading the secondary replica to SQL Server 2014, when AlwaysOn fails over, the secondary replica acts as primary replica. Then once AlwaysOn fails over again, the upgraded primary replica can no longer ship logs to any secondary replica that has not yet been upgraded to SQL Server 2014. Therefore, the best choice is to perform a rolling upgrade for the Availability Group Servers in your scenario.

    For more details, please review the following article.
    Upgrade and Update of Availability Group Servers with Minimal Downtime and Data Loss: http://msdn.microsoft.com/en-us/library/dn178483.aspx


    Thanks,
    Lydia Zhang

    • Marked as answer by Antoine F Monday, October 27, 2014 3:46 PM
    Monday, October 27, 2014 8:12 AM
  • Thank you Lydia, this is exactly what I needed!

    I notice once you updated the "non primary replica" and perform the manual failover you do not even need to remove the previous primary from the availability group. Even simplier than I thought!

    Monday, October 27, 2014 3:50 PM