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Disaster Recovery and High Availability Solutions in SQL Server

  • April 15, 2024 at 12:00 am

    #4397519

    Comments posted to this topic are about the item Disaster Recovery and High Availability Solutions in SQL Server

  • April 17, 2024 at 8:25 pm

    #4412530

    It would have been helpful to know what prerequisites are required for a command to run successfully. For example,

    -- Run this on each server instance participating in the AG.
    EXEC sp_configure 'hadr enabled', 1;
    RECONFIGURE;

    returned

    Msg 15123, Level 16, State 1, Procedure sp_configure, Line 62 [Batch Start Line 9]
    The configuration option 'hadr enabled' does not exist, or it may be an advanced option.

    It was not in Advanced Options. In documentation, I found this T-SQL code instead:

    SELECT SERVERPROPERTY ('IsHadrEnabled');

    and becomes enabled either in Management Studio or in PowerShell with

    Enable-SqlAlwaysOn -Path SQLSERVER:\SQL\Computer\Instance

    • This reply was modified 1 year, 5 months ago by andre.quitta.

  • April 17, 2024 at 11:01 pm

    #4412560

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  • August 26, 2025 at 11:38 pm

    #4641280

    I'm curious if you could help me better understand the given disaster recovery scenario:

    Disaster Scenario and Response

    When the primary data center was hit by a natural disaster, the company's investment in a multi-tiered DR strategy paid off:

    1. Failover to DR Site: Automated failover mechanisms for Always On AGs were triggered, promoting the asynchronous-commit replicas to primary status. This process was smooth and rapid, thanks to regular testing and a well-documented failover procedure.
    2. Log Shipping Role Switch: Manual intervention was required to bring the log-shipped databases online at the DR site. Although this process took longer than the AG failover, the impact was mitigated by the non-critical nature of the affected databases.

    Can you elaborate on 1. If there is "automatic" failover mechanism, what is to prevent that mechanism from "kicking in" when there happens to just be a short network outage? If the failover is automatic and it were to happen when the primary data center was still operational, you would end up with the situation of having two primary SQL Servers running and accepting writes at the same time. Then what would happen after the temporary network outage was fixed?

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