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  1. #1
    Join Date
    Oct 2012
    Posts
    1

    Unanswered: swap memory usage while increasing db size

    I am using Informix 11.7 and I got a requirement to increase the DB Size. But on increasing the Db Space, I can see swap memory being used on my system (in my environment DB shares memory with many other applications). I have set SHMTOTAL as 1 GB but still memory consumption through TOP seems quite high.
    Need to understand if I am using the right approach to get the memory consumption of Informix.

    Although onstat –g seg suggest on Virtual segment being added to server.

    cucdb onstat -g seg
    Segment Summary:
    id key addr size ovhd class blkused blkfree
    4063244 52604801 44010000 328232960 2146492 R* 80133 2
    4390934 5260480b 57917000 268435456 1574024 V 25298 40238
    Total: - - 596668416 - - 105431 40240


    TOP Output
    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

    9097 informix 5 -10 594m 306m 305m S 1.3 3.8 4:47.27 unityoninit
    9104 informix 5 -10 594m 235m 234m S 8.0 3.0 14:43.94 unityoninit
    9105 informix 5 -10 594m 198m 196m S 0.0 2.5 1:20.48 unityoninit
    9101 root 5 -10 592m 117m 115m D 0.3 1.5 1:32.43 unityoninit
    9118 root 5 -10 592m 115m 114m S 0.0 1.4 0:57.19 unityoninit
    9119 root 5 -10 592m 111m 110m S 0.0 1.4 0:41.59 unityoninit
    9120 root 5 -10 592m 111m 110m S 0.0 1.4 0:14.50 unityoninit
    9121 root 5 -10 592m 108m 107m S 0.0 1.4 0:01.25 unityoninit
    9122 root 5 -10 592m 91m 90m S 0.0 1.1 0:00.31 unityoninit
    9131 root 5 -10 592m 70m 69m S 0.0 0.9 0:00.23 unityoninit
    9132 root 5 -10 592m 44m 43m S 0.0 0.6 0:00.13 unityoninit


    but the sum of RES column in TOP for various instances of informix is 1506MB

    Thanks

  2. #2
    Join Date
    Sep 2011
    Location
    Pont l'Abbé, Brittany, France
    Posts
    381
    Provided Answers: 1
    Hi,

    I'm not sure about what you mean when you say "increase db size".
    If you mean "increase disk space for Informix", this action has absolutely no consequence on the memory consumption. I think you are confusing between increasing BUFFERPOOL, which will definately have consequences on the memory consumption, and enlarging disk space.
    I have a feeling you are meaning enlarging disk space. Generally, this is done using the onspaces command, which allows you to add a chunk to an existing dbspace
    See at this place
    how to use onspaces.

    Another great feature introduced in 11.70 is the Storage Pool, which allows you to declare chunks as automatically extendable. Reaching a determined threshold, Informix will automatically extend the chunk size with any human action.
    TO understand Storage Pool, check here

    If you are meaning increasing the Informix shared memory, please specify why you have to do it and what is your objective.

    Thx
    E.

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