Changing recovery model

  • Hi,

    Do I have any impact on changing recovery model in SQL Server 2005 when the database is online? More over is there any impact in changing the Initial size of the log files (Currently the Recovery model is FULL).

    Thank You

  • If you switch from the full recovery model to the simple recovery model you break the backup log chain. Therefore, strongly recommend that you back up the log immediately before switching, which allows you to recover the database up to that point. After switching, you need to take periodic data backups to protect your data and to truncate the inactive portion of the transaction log.

    You can increase the size of log file

  • Hi,

    Thanks for the reply, do I have any impact on changing the database recovery model while the database is in live. And more over I have the Initial size of log files is 50 GB I need to reduce it to 50 MB is that will create any problems.

    Thank You

  • No impact other than that you will no longer be able to take log backup and hence will not be able to restore to a point-in-time after switching to simple. Also if you are running database mirroring you will not be able to switch from full recovery

    You can shrink the log to 50MB, but if the DB is active there's every chance it will grow again. 50MB is very small for a transaction log for an active database.

    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

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • What would happen if I switched from Full to Simple to Full in a stored procedure?

    When I back up the transaction log after I set it back to Full, would it be able to know that there was a full database backup (.bak)? I am running SQL Server 2008.

  • Please post new questions in a new thread. Thank you.

    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

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • GilaMonster (9/17/2008)


    No impact other than that you will no longer be able to take log backup and hence will not be able to restore to a point-in-time after switching to simple. Also if you are running database mirroring you will not be able to switch from full recovery

    You can shrink the log to 50MB, but if the DB is active there's every chance it will grow again. 50MB is very small for a transaction log for an active database.

    How much of a performance hit (a little, moderate, A LOT, don't do it, etc.) is there from shrinking the log file? The reason I ask is I'm faced with a situation where a production database has a much larger log file than is necessary. The database in question is a production database and it is pretty much used 24/7, so I'm attempting to find out if it is 'okay' or feasible to perform the action of shrinking a 100 GB .ldf during production hours.

    The following was suggested to me in order to fix the matter:

    1. Backup the TLOG

    2. Change DB from Full to Simple

    3. Change the initial size of the TLOG to something much smaller

    4. Perform the log shrink

    5. Change from Simple to Full

    6. Perform full backup of DB to start log chain

    Is this proper? If not, what would your process be to fix this matter?


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  • GilaMonster (4/11/2011)


    Please post new questions in a new thread. Thank you.

    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

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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