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  1. #1
    Join Date
    Nov 2003
    Posts
    1

    Unanswered: old buffer aging bug

    What is an old buffer aging bug?
    When I running onstat -P, I get

    Percentages:
    Data 12.30
    Btree 86.78
    Other 0.93


    What do I should to do?

    I am running Informix Dynamic Server 2000 Version 9.21.UC1 on Solaris 2.7.

    I have performance problems.

    In ONCONFIG I defined:

    NETTYPE tlitcp,,,
    DEADLOCK_TIMEOUT 60
    RESIDENT 1
    MULTIPROCESSOR 1
    NUMCPUVPS 1
    SINGLE_CPU_VP 1
    NOAGE 1
    AFF_SPROC 1
    AFF_NPROCS 1

    LOCKS 200000
    BUFFERS 250000
    NUMAIOVPS 2
    PHYSBUFF 64
    LOGBUFF 4
    LOGSMAX 50
    CLEANERS 1
    SHMBASE 0xa000000
    SHMVIRTSIZE 8000
    SHMADD 8192
    SHMTOTAL 0
    CKPTINTVL 300
    LRUS 8
    LRU_MAX_DIRTY 60
    LRU_MIN_DIRTY 50
    LTXHWM 50
    LTXEHWM 60
    TXTIMEOUT 0x12c
    STACKSIZE 32


    Thanks.

    ----- Original Message -----
    From: "Art S. Kagel" <kagel@bloomberg.net>
    Newsgroups: comp.databases.informix
    Sent: Monday, October 27, 2003 16:11
    Subject: Re: how to use onstat -P


    > On Sun, 26 Oct 2003 21:32:56 -0500, dusong wrote:
    >
    > There are three areas of interest on an onstat -P report.
    >
    > 1) The first line: Looking at the partnum zero (0) line, the page count in the
    > 'other' column is an indication of the number of buffer cache pages that are
    > currently unused since besides unused pages the number of pages that actually
    > fall under the 'other' heading is tiny.
    >
    > A persistent high number here can indicate that you may be able to reduce the
    > number of BUFFERS without affecting performance. However, be sure to check
    > during peak loads to be certain.
    >
    > 2) The summary at the bottom. In a healthy OLTP/DSS environment there is
    > normally a ratio of about 60-80% data pages, 15-35% index (BTree) pages and a
    > small 'other' (excluding any excess 'other' noted above). Btree is normally
    > about 1/3 of the Data value. Obviously in a DW environment with far fewer
    > indexes this ratio will not hold. Note that if you are running an early 7.3 or
    > 9.2 release and the Btree value is over 60% you may be running into an old
    > buffer aging bug.
    >
    > 3) Each partnum line. You can use this information to determine what tables and
    > or indexes are being heavily hit and may benefit from fragmentation over several
    > dbspaces to spread the load and take advantage of parallel scans. Also for
    > smaller tables - noticing a lookup table whose page count flutuates from most
    > of the table's pages to very few many times a day may identify a candidate
    > table to be marked RESIDENT.
    >
    > Art S. Kagel
    >
    >
    >
    >
    >
    > > How to use onstat -P(not -p) to tell informix server's performance question:?
    > >
    > >
    > > --
    > > Posted via http://dbforums.com

  2. #2
    Join Date
    Aug 2003
    Location
    Argentina
    Posts
    780

    Re: old buffer aging bug

    Originally posted by svetlzh
    What is an old buffer aging bug?
    When I running onstat -P, I get

    Percentages:
    Data 12.30
    Btree 86.78
    Other 0.93


    What do I should to do?

    I am running Informix Dynamic Server 2000 Version 9.21.UC1 on Solaris 2.7.

    I have performance problems.

    In ONCONFIG I defined:

    NETTYPE tlitcp,,,
    DEADLOCK_TIMEOUT 60
    RESIDENT 1
    MULTIPROCESSOR 1
    NUMCPUVPS 1
    SINGLE_CPU_VP 1
    NOAGE 1
    AFF_SPROC 1
    AFF_NPROCS 1

    LOCKS 200000
    BUFFERS 250000
    NUMAIOVPS 2
    PHYSBUFF 64
    LOGBUFF 4
    LOGSMAX 50
    CLEANERS 1
    SHMBASE 0xa000000
    SHMVIRTSIZE 8000
    SHMADD 8192
    SHMTOTAL 0
    CKPTINTVL 300
    LRUS 8
    LRU_MAX_DIRTY 60
    LRU_MIN_DIRTY 50
    LTXHWM 50
    LTXEHWM 60
    TXTIMEOUT 0x12c
    STACKSIZE 32


    Thanks.

    ----- Original Message -----
    From: "Art S. Kagel" <kagel@bloomberg.net>
    Newsgroups: comp.databases.informix
    Sent: Monday, October 27, 2003 16:11
    Subject: Re: how to use onstat -P


    > On Sun, 26 Oct 2003 21:32:56 -0500, dusong wrote:
    >
    > There are three areas of interest on an onstat -P report.
    >
    > 1) The first line: Looking at the partnum zero (0) line, the page count in the
    > 'other' column is an indication of the number of buffer cache pages that are
    > currently unused since besides unused pages the number of pages that actually
    > fall under the 'other' heading is tiny.
    >
    > A persistent high number here can indicate that you may be able to reduce the
    > number of BUFFERS without affecting performance. However, be sure to check
    > during peak loads to be certain.
    >
    > 2) The summary at the bottom. In a healthy OLTP/DSS environment there is
    > normally a ratio of about 60-80% data pages, 15-35% index (BTree) pages and a
    > small 'other' (excluding any excess 'other' noted above). Btree is normally
    > about 1/3 of the Data value. Obviously in a DW environment with far fewer
    > indexes this ratio will not hold. Note that if you are running an early 7.3 or
    > 9.2 release and the Btree value is over 60% you may be running into an old
    > buffer aging bug.
    >
    > 3) Each partnum line. You can use this information to determine what tables and
    > or indexes are being heavily hit and may benefit from fragmentation over several
    > dbspaces to spread the load and take advantage of parallel scans. Also for
    > smaller tables - noticing a lookup table whose page count flutuates from most
    > of the table's pages to very few many times a day may identify a candidate
    > table to be marked RESIDENT.
    >
    > Art S. Kagel
    >
    >
    >
    >
    >
    > > How to use onstat -P(not -p) to tell informix server's performance question:?
    > >
    > >
    > > --
    > > Posted via http://dbforums.com
    Hi,

    The output of onstat -P is not bad.
    I think you test changed :
    MULTIPROCESSOR 0
    NOAGE 0
    AFF_SPROC 0
    AFF_NPROCS 0

    I need know about you environment for example layout of disk, physical memory, checkpoint time.

    Can you send me this infromation ?

    Gustavo.

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