log file sync
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  1. #1
    Join Date
    Mar 2004
    Location
    IA USA
    Posts
    257

    log file sync

    DBAs,

    We recently got a lot of complaints about one database for its slowness.
    I took a snapshot during the slow time whose time window is 15 minuets.
    From the stats report, in the top 5 waits, we saw the log file sync.
    How can we know it is abnormal or normal?

    The important part in the report is as follows:
    Code:
    Instance Efficiency Percentages (Target 100%)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                Buffer Nowait %:  100.00       Redo NoWait %:  100.00
                Buffer  Hit   %:   99.24    In-memory Sort %:   99.96
                Library Hit   %:   85.99        Soft Parse %:   44.28
             Execute to Parse %:   15.49         Latch Hit %:   98.70
    Parse CPU to Parse Elapsd %:   89.44     % Non-Parse CPU:   55.74
    
    
    Top 5 Wait Events
    ~~~~~~~~~~~~~~~~~                                             Wait     % Total
    Event                                               Waits  Time (cs)   Wt Time
    -------------------------------------------- ------------ ------------ -------
    log file sync                                      61,458        7,386   47.32
    latch free                                         20,065        3,686   23.61
    db file sequential read                            17,752        1,641   10.51
    log file parallel write                            56,093        1,610   10.31
    db file parallel write                              1,610          908    5.82
              ------------------------------------------------------
    
    Event                               Waits   Timeouts  Time (cs)    (ms)   /txn
    ---------------------------- ------------ ---------- ----------- ------ ------
    log file sync                      61,458          0       7,386      1    1.0
    latch free                         20,065     15,166       3,686      2    0.3
    db file sequential read            17,752          0       1,641      1    0.3
    log file parallel write            56,093          0       1,610      0    1.0
    db file parallel write              1,610          0         908      6    0.0
    
    
    Statistic                                    Total   per Second    per Trans
    --------------------------------- ---------------- ------------ ------------
    CPU used by this session                    35,105         39.0          0.6
    Any idea from this report?

    Thnaks for the help.
    Last edited by marist89; 09-28-2005 at 03:49 PM. Reason: formatting

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