May 6, 2016 at 6:28 am
hello everybody
is it possible to connect two or more different versions of sql server instances via always on?
(like SQL 2014 and SQL 2016)
thx
May 6, 2016 at 6:36 am
No (with caveat).
The root reason here is that databases cannot be downgraded, nor can log structures. So while it should be possible to have a primary replica on 2014 and a secondary replica on 2016, the minute you failover to the 2016 instance you would break the AG and never be able to fail back to the original primary. A HA/DR solution that you can't failover isn't all that useful.
The caveat is that, as far as I'm aware, AGs with different versions are possible and supported ONLY as part of the process of a rolling upgrade. The idea there is that you have two servers on SQL 2014 in an AG and you want to upgrade to SQL 2016 with minimal downtime, you would upgrade the secondary to SQL 2016, now you have the different versions, then failover to the secondary, then upgrade the primary to SQL 2016 and (optionally) fail back to the original primary. Complete version upgrade with only as much downtime as is required by one or two controlled failovers.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
May 6, 2016 at 6:40 am
that's exactly what i meant
we may upgrade some of our installations to 2016. we have 3 replicas and we would want to upgrade them with minimum downtime. if it works the way you described, i'd go that way.
thanks
May 6, 2016 at 6:44 am
In that case, it should be fine. Start with all SQL 2014 replicas in an AG and upgrade them one by one.
https://msdn.microsoft.com/en-us/library/dn178483.aspx
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
January 8, 2020 at 10:11 pm
Can you build a 2 node Always on cluster where node1 has a sql2016instance and a sql2017instance and node2 has a sql2016instance and a sql2017instance and then create an availability group and listener between node1 SQL2016instance and node2 sql2016instance, and then a 2nd availability group and listener between node1 sql2017instance and node2 sql2017instance?
August 29, 2022 at 1:36 pm
Yes, you can do so with no issues.
September 17, 2022 at 6:33 pm
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