Select between GDR and CU

asked 2020-08-27T20:44:45.89+00:00
DBA 21 Reputation points

I have Sql server 2014 in always-on , When i did Microsoft security upgrade primary shows as (SP2-CU18) and secondary shows as (SP2-GDR).

Why there is a difference as primary is CU and secondary GDR.?

historically primary was upgrading only CU and secondary was upgrading GDR, I read that there is no going back from CU to GDR or GDR to CU?

if so, what makes the sql server to decide to go for GDR or CU ?

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  1. answered 2020-08-28T02:00:30.863+00:00
    CathyJi-MSFT 20,656 Reputation points Microsoft Employee

    Hi @DBA ,

    SQL Server 2014 SP2 GDR update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically. SQL 2014 SP2-GDR is an older version than SQL server 2014 SP2 CU18. It seems someone only apply the CU18 to the primary node of AG, and did not apply it to secondary. So the version is difference.

    According to MS document SQL Server Instance Prerequisites for AG, each server instance must be running the same version of SQL Server to participate in an Always On Availability Group. Please apply SP3 for SQL 2014 and apply CU4 for SQL 2014 SP3. We can rolling upgrade SQL AG, please follow the steps from this document Upgrading Always On Availability Group Replica Instances.

    Best regards,
    Cathy

    ===============================================

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  1. answered 2020-08-27T21:20:39.24+00:00
    Erland Sommarskog 67,481 Reputation points Microsoft MVP

    There is a difference because someone at your side decided to only apply CU on the primary. The GDR is pushed out through Windows Update. The CUs are not.

    As it happens, both versions are out of date. The final version of SQL 2014 is SP3 CU4, and I think there is a GDR on top of that. I would recommend that you apply these updates in your next maintenance window.

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