Recovery mode reverting to Full

  • Perhaps I am missing something 'Simple'...

     I am running an instance on AWS RDS..

    I am trying to set the recovery mode of a database to simple eg:
    ALTER DATABASE [Test] SET RECOVERY SIMPLE

    his works fine, and I can see the change BUT, after a few minute it reverts back to FULL?? Am I  missing something?

  • Perhaps this might help: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.SQLServer.CommonDBATasks.DatabaseRecovery.html

    Specifically:

    Changing a database’s recovery model to “Simple” while backup retention is           enabled will result in Amazon RDS setting the recovery model to “Full” within           five           minutes of the setting change. This will also result in Amazon RDS taking a snapshot           of the DB instance.          

    Thom~

    Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
    Larnu.uk

  • sharky - Thursday, April 26, 2018 5:31 AM

    Perhaps I am missing something 'Simple'...

     I am running an instance on AWS RDS..

    I am trying to set the recovery mode of a database to simple eg:
    ALTER DATABASE [Test] SET RECOVERY SIMPLE

    his works fine, and I can see the change BUT, after a few minute it reverts back to FULL?? Am I  missing something?

    RDS is supposed to be fully managed service, why would you want to change the recovery model when you cannot control or manage it? 
    😎
    The only thing you could possibly accomplish would be breaking the log chain!

  • Thom, Erikur,  Thanks for the help.. Understand a bit more how AWS works.. thanks.. The problem was that the log was growing to a few gig (log_Reuse_Wait_description = LOG_BACKUP in sys.databases.) My next question would be why would this be If is a mananged service, Surely the log should not grow and should be backed up and truncated? ? We ran out of space because of the issue. Our SLA's don't really require the logs to be backed up, so simple is fine. I don't want the log to keep growing though until we run out of space!

  • sharky - Thursday, April 26, 2018 6:25 AM

    Thom, Erikur,  Thanks for the help.. Understand a bit more how AWS works.. thanks.. The problem was that the log was growing to a few gig (log_Reuse_Wait_description = LOG_BACKUP in sys.databases.) My next question would be why would this be If is a mananged service, Surely the log should not grow and should be backed up and truncated? ? We ran out of space because of the issue. Our SLA's don't really require the logs to be backed up, so simple is fine. I don't want the log to keep growing though until we run out of space!

    Did you find a resolution for this?

    --Jeff Moden


    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

    Change is inevitable... Change for the better is not.


    Helpful Links:
    How to post code problems
    How to Post Performance Problems
    Create a Tally Function (fnTally)

  • Thom A - Thursday, April 26, 2018 5:34 AM

    Perhaps this might help: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.SQLServer.CommonDBATasks.DatabaseRecovery.html

    Specifically:

    Changing a database’s recovery model to “Simple†while backup retention is           enabled will result in Amazon RDS setting the recovery model to “Full†within           five           minutes of the setting change. This will also result in Amazon RDS taking a snapshot           of the DB instance.          

    +1

    ...

  • Jeff.. What I did in the end was to set the database to simple and immediately did a DBCC shrinkfile of the log files before it reverted back to full. The  problem started when the client restored the previous non RDS databases (all in Full recovery without ever taking log backups) on a new RDS instance. The RDS  backup was not able to truncate the log and it kept growing. At first I was confused why AWS would allowed the database to be set to simple in the first place, but as it provided a nice workaround ( perhaps by design although I could not found this documented??) it saved me a lot of work and don't complain to much..

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