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AIX 7.1 Oracle 11g(11.2.0.4) frequent paging but no scaning in nMon

  • 1.  AIX 7.1 Oracle 11g(11.2.0.4) frequent paging but no scaning in nMon

    Posted Fri October 23, 2015 02:49 AM

    Originally posted by: aks1


    Hi Guys

     

    I am running performance test suite on my application with Weblogic11(10.3.6) and Oracle 11g DB(11.2.0.4) on AIX7.1. While CPU and memory utilization on app server and DB srever seems normal, response time is not coming down, as per DBA there no significant scope for query tuning.

    We have captured Nmon logs and per NMon graphs(vai nMon Analyser), i saw some spikes after 12-13 mins on DB sever, thse spikes are visible in memory,CPU and Disk busy stats. Also on the paging sheet, there's significant paging out but no scanning.

     

    Report Time

    Base Vol

    User

    Server

    VCPUS

    RAM(GB)

    Avg %

    Max %

    Avg %

    Max %

    Max DB
    Seesion

    DB

     Updates

    Txn>5Sec

     11:45 to 13:15

    10L

    500

    App Server

    12

    24

    16

    38

     

     

    338

    96.094

    35.26%

    DB Server

    12

    24

    39.5

    86

     

     

    NMon Analyser Graphs(DB Server):

    vm_tune (MEMUSE sheet of NMon )DB Server

    Here are some of the vmo parameters from DB Server

     

    bash-3.2# oslevel -r

    7100-03

    bash-3.2# lsps -s

    Total Paging Space   Percent Used

          16384MB               0%

     

    bash-3.2# swap -l

    device              maj,min        total       free

    /dev/hd6              10,  2     16384MB     16315MB

     

    bash-3.2# lsps -a

    Page Space      Physical Volume   Volume Group    Size            %Used Active  Auto  Type Chksum

    hd6                       hdisk0                    rootvg                  16384MB     0       yes        yes      lv     0

     

    bash-3.2# uptime

      11:40AM   up 255 days,  16:46,  5 users,  load average: 1.29, 1.28, 1.27

     

    bash-3.2# vmo -o defps

    defps = 1

     

    vmo parameters

    minfree = 960

    maxfree = 1088

    minperm = 180899

    maxperm = 5426999

    maxpin = 5687744

    minperm% = 3

    numperm%= 56.6

    maxpin% = 90

    maxperm% = 90 (vmstat -v)

    maxclient%=90 (vmstat -v)

    numclient%= 56.6 (vmstat -v)

    low_ps_handling = 1

    j2_maxPageReadAhead = 128(ioo -a -F | grep head)

     j2_minPageReadAhead = 2

     maxpgahead = 8

     minpgahead = 2

     

    bash-3.2# vmstat -v shows 2 memory pools

     

    Some key entries from MEM sheet of nMon

     

    Paging AIX4-11-13

    faults

    pgin

    pgout

    pgsin

    pgsout

    reclaims

    scans

    cycles

    fsin

    fsout

    sr/fr

    11:50:59

    6944

    0.6

    1321.8

    0

    0

    0

    0

    0

    0.6

    1321.8

    0.0

    11:51:04

    3450.1

    2.8

    3935.1

    0

    0

    0

    0

    0

    2.8

    3935.1

    0.0

    11:52:49

    3669.4

    4.4

    8051.5

    0

    0

    0

    0

    0

    4.4

    8051.5

    0.0

    12:07:59

    1778.4

    11.8

    1726.7

    0

    0

    0

    0

    0

    11.8

    1726.7

    0.0

    12:08:04

    859

    6.4

    6592.6

    0

    0

    0

    0

    0

    6.4

    6592.6

    0.0

    12:21:14

    2280.8

    1

    8084.4

    0

    0

    0

    0

    0

    1.0

    8084.4

    0.0

    12:33:14

    1523.7

    0.8

    8382

    0

    0

    0

    0

    0

    0.8

    8382.0

    0.0

    12:47:04

    1298.4

    0.2

    8236.5

    0

    0

    0

    0

    0

    0.2

    8236.5

    0.0

    13:00:10

    1038.6

    0

    9044

    0

    0

    0

    0

    0

    0.0

    9044.0

    0.0

    13:12:40

    3460.1

    4.4

    8349.4

    0

    0

    0

    0

    0

    4.4

    8349.4

    0.0

    SGA memory details of the database are as follow:

    SGA - 2GB

    PGA - 0

    Memory_Target - 3GB

    Can some one tell me whats wrong going on the DB Srever?

    Thanks in advance



  • 2.  Re: AIX 7.1 Oracle 11g(11.2.0.4) frequent paging but no scaning in nMon

    Posted Thu December 10, 2015 07:44 AM

    Originally posted by: HajoEhlers


    As you can see there is no paging to or from pagaing space.

    The paging should be from reading files ( binaries ) from disk and is for the given intervall not much.

     

    all imho

    Hajo



  • 3.  Re: AIX 7.1 Oracle 11g(11.2.0.4) frequent paging but no scaning in nMon

    Posted Mon December 14, 2015 09:11 AM

    Originally posted by: AncientAIXer


    The pgin/pgout is not paging to paging space.  It is paging associated with freeing memory when needed.  pgsin/pgsout is the paging to paging space.  The minfree is 960 (pages) and the maxfree is 1088.  Assuming 4K pages, that is only 3.75 and 4.25 Mb free.  I don't know of many database related processes that are less than or equal to 4 Mb.  Therefore, the system must decided which memory pages can be released before a process could be loaded into memory.  There is used memory, cached memory, and free memory.  When "free" memory gets to minfree, the system will start discarding old cached pages until maxfree is available.  That takes time.  You don't mention how much memory you have but it appears that you have at least 8 Gb, if not 16 Gb.  With that size of system, I would set maxfree to at least 128 or 256 Mb and minfree to half maxfree or less.

    Unfortunately, performance tuning is not stressed as much as it should be in AIX or Unix for that matter.  Most of the tuning settings in AIX are defaulted to the lowest common denominator.  Not necessarily fact now days, but for example it may be defaulted to settings for 10 Mb Ethernet, which is not good for a system that has 10 Gb Ethernet.  The memory is defaulted to the minimum recommended memory for AIX.  Settings for 128 Gb memory would not be a good default for a system with only 2 Gb.  A system should be tuned before any non-AIX programs are even installed and definitely before the system is put into production.  My $.02 worth.  I'll get off my soap box now...



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