Log File & Performance

  • Hello everyone,

    M friends are telling that moving the DB log to a separater partition improves the performance. Is this true? If so How?

    Thanks

    Stephen

  • From benchmarks I have run using SQLIOStress, having the data and log files on separate RAID-1 drives increases thruput by a factor of 6 compared to both on the same drive.

    But if the log and data file are on a different partition of the same physical drive, I would expect some gain but not sure how much.

    You can use the SQL IO simulator to run some benchmarks.

    http://support.microsoft.com/default.aspx?scid=kb;EN-US;231619#2

    Of course, this only applies to local disks and SANs are a completely different question.

    SQL = Scarcely Qualifies as a Language

  • You said it will increase the performance if it is two different partition. What makes you tell that like is there any specific process that happens each time you do some DB activities.

  • Yes, moving a logfile to a different physical disk will always increase IO, because you're spreading your IO. But howmuch it will improve depends on your databasetype. If it's generating a lot of logging, you'll notify the difference.

    If that's not the case, consider moving your indexes to a different physical disk.

    Wilfred
    The best things in life are the simple things

  • stephensunil (6/6/2008)


    M friends are telling that moving the DB log to a separater partition improves the performance. Is this true?

    It can be, but only if the partition is on separate physical devices. Moving the logfile to a partition on the same physical devices will actually make performance worse.

    [font="Times New Roman"]-- RBarryYoung[/font], [font="Times New Roman"] (302)375-0451[/font] blog: MovingSQL.com, Twitter: @RBarryYoung[font="Arial Black"]
    Proactive Performance Solutions, Inc.
    [/font]
    [font="Verdana"] "Performance is our middle name."[/font]

  • Rbarryyoung is right there.

    If you have a lot of database activity that causes loggin going then it makes sense to move the log file to a separate disk. Other wise think about moving your indexes or move some of those tables that have the most activity going on. In this way you will be spreading your IO across different disks.

    "Keep Trying"

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