Queue length ?
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  1. #1
    Join Date
    Sep 2000
    Posts
    64
    Hello,

    I find the following explanation of Dirty Queue Length & Write Requests :

    Dirty Queue Length - Value for dirty queue length
    Write Requests - Value for write requests (total)
    Write Request Queue Length - Average request queue length

    Could you give me more explanations (clear explanation) about the Dirty Queue Length & Write Requests.


    Thanks a lot

    Sofiane
    Sofiane

  2. #2
    Join Date
    Feb 2001
    Posts
    389
    Dirty queue length:

    The number of dirty buffers in buffer cache to be cleared by DBWR , should be zero or increase number of DBWR if it is consistently high.

    Write requests : Writes by LGWR , if it is high and log file sync is high, tune log_buffer

  3. #3
    Join Date
    Sep 2000
    Posts
    64
    thanks gpsingh

    What's about the Average Request Queue Length (How is is interpreted).

    Thanks in advance

    Sofiane
    Sofiane

  4. #4
    Join Date
    Feb 2001
    Location
    Bombay,India
    Posts
    530
    Hi,

    Write requests
    This statistics stores the number of times DBWR takes a batch
    of dirty buffers and writes them to the disk

    Dirty Queue Length
    After every write request the dirty LRU queue length.
    i.e the leftover no of dirty buffers which are waiting to
    be written to the disk.


    If any doubts,please be free to write to
    rohitsn@orasearch.net

    regards,
    Rohit Nirkhe,Oracle DBA,OCP

  5. #5
    Join Date
    Feb 2001
    Posts
    389
    correction
    write requests
    This statistic stores the number of times DBWR (not LGWR) takes a batch of dirty buffers and writes them to disk.
    But if log_file_sync is high , you have to tune log_buffer

    And

    SELECT SUM(DECODE(name,'summed dirty queue length',value)) /
    SUM(DECODE(name,'write requests',value)) "Write Request Length"
    FROM v$sysstat WHERE name IN ( 'summed dirty queue length','write requests')
    AND value > 0;

    If this value is larger than 1/4(db_block_buffers) increase db_file_simultaneous_writes.

  6. #6
    Join Date
    Sep 2000
    Posts
    64
    Thanks a lot for these information
    Sofiane

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