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JohannesMaly-3567 asked ErlandSommarskog commented

SQL Server 2019 Read-Scaling with mixed Server Versions

I would like to know if it is possible and legal to create a read-only replica of a database hosted on a SQL Server 2019 Enterprise on a SQL Server 2019 Standard Edition.

Concrete I would like to use the AG feature to decouple reporting tasks from the Enterprise Server and just replicate one or more DB's to a much cheaper Standard Edition Server. So far I only found basic information on how read-scaling could be setup but no details about licensing issues.

Of course a second SQL Server 2019 Enterprise license is quite a bunch of money for just having a DB replicated for reporting tasks.
In my scenario failsafe clustering feature is off topic. The reporting server is not mission critical.

Any help or ideas are welcome

Regards
Johannes

sql-server-general
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ErlandSommarskog avatar image
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ErlandSommarskog answered ErlandSommarskog commented

I don't think that is possible. The only sort of AG you can create on a Standard Edition is a Basic Availability Group, which is a two-node AG with no readable secondary. I can't say for sure that it cannot be clusterless (i.e. read-scale), but since it cannot be readonly, there is little point in any way.

If you want this combo, you may want to consider log shipping or transactional replication.

You would have to be little careful and not use features not supported on Standard Edition, although that is less of problem these days.

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Actually I'm wondering why that is not possible. I touhgt that having a fully licensed SQL Server 2019 Enterprise Server and a second one with a fully licensed SQL Server 2019 Standard Server a read only replica from Enterprise to Standard should be possible (https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/read-scale-availability-groups?view=sql-server-ver15) . My idea was to create a Read-scale availability group without a cluster and use the Standard Edition Server only for reporting purpose.

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There is a very simple reason why it is not possible. Availability Groups is essentially an Enterprise feature. But to permit sites on Standard Edition to move off from Database Mirroring, which have been deprecated, they introduced this very special constrained version Basic Availability Group.

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Yufeishao-msft avatar image
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Yufeishao-msft answered

Hi @JohannesMaly-3567,

You may not achieve your goal.
Each server instance must be running the same version of SQL Server to participate in an Always On Availability Group.
https://docs.microsoft.com/zh-cn/sql/database-engine/availability-groups/windows/prereqs-restrictions-recommendations-always-on-availability?view=sql-server-ver15#sql-server-instance-prerequisites-and-restrictions

for read-only replica, may be transaction replication suit your problem


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