DB .mdf file Increasing Beyond Autogrowth Size

  • Our primary DB is ~400GB, and the last time the .mdf primary data file grew, it expanded by 20%, instead of the 10% that it was set at. A month ago, I set the autogrowth to 5%. However, when it grew last week, it expanded by 10% instead of 5%.

    The log is set to 10% autogrowth, but the data is set to 5%. Any idea why the last two growth sessions increased double what they were set to autogrow as?

  • bdragoo (7/21/2009)


    Our primary DB is ~400GB, and the last time the .mdf primary data file grew, it expanded by 20%, instead of the 10% that it was set at. A month ago, I set the autogrowth to 5%. However, when it grew last week, it expanded by 10% instead of 5%.

    The log is set to 10% autogrowth, but the data is set to 5%. Any idea why the last two growth sessions increased double what they were set to autogrow as?

    How about providing actual growth in MB instead of %. It is hard to answer your question without firm data.

  • there is also a bug in SQL 2005 with autogrowth when you restore a db or restart the services etc.

    In the view sys.database_files is_growth_percent changes from 0-1, which means that earlier the value in mb is converted to percent, it happened to me many times, be aware of that.

    Its always better to have the auto-growth value is MB instead of percent, as sys has to use many resources to calculate the value!!!

  • A guess:

    Database size (in MB) Growth (@ 10%)

    100 10

    110 11

    121 12.1

    133.1 13.31

    146.41 14.641

    Does that make sense?

    You really should set the the log and data files to grow a set size every time instead of a given percentage. using a percentage, each time it grows it will grow by a large amount.

  • dba_pkashyap (7/21/2009)


    there is also a bug in SQL 2005 with autogrowth when you restore a db or restart the services etc.

    In the view sys.database_files is_growth_percent changes from 0-1, which means that earlier the value in mb is converted to percent, it happened to me many times, be aware of that.

    Its always better to have the auto-growth value is MB instead of percent, as sys has to use many resources to calculate the value!!!

    Is this bug documented somewhere? I have never had an issue with it and I am curious.

  • I havent seen it documented anywhere, but I had it in my experience many times.

    Autogrowth value going to 6-7digit as percentage!!!

  • This issue was first reported here: http://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=127177

    And, fixed here: http://support.microsoft.com/kb/919611/

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