Db2 (On Premises and Cloud)

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dmc and memory

  • 1.  dmc and memory

    Posted Wed June 09, 2021 05:34 AM
    as we get notifications in dmc about memory usage I had a  look
    the screen indicates 25G of memory
    looking at top
    KiB Mem : 26568712 total, 504640 free, 4257068 used, 21807004 buff/cache
    KiB Swap: 8387580 total, 1744800 free, 6642780 used. 8545776 avail Mem
    we have 26G memory and 8G swap : total should be 34G ?



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    Thank for all update/help
    Best Regards, Guy Przytula
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  • 2.  RE: dmc and memory

    Posted Wed June 23, 2021 01:55 PM
    Hi Guy,

    The virtual memory alert is calculated based on:

    virtual_mem_total - virtual_mem_free / virtual_mem_total * 100

    And
    virtual_mem_total = memory_total + memory_swap_total
    virtual_mem_free = memory_free + memory_swap_free

    In your example, it would be:

    (26568712 + 8387580) - (504640 + 1744800) / (26568712 + 8387580) = 100  i.e. ~93% at the moment you took the "top" snapshot.

    Looking at the "top" output, seems like swap used (swap total - swap free) is 6642780.  Indicating some swapping in your system.  You may want to see why sudden swapping is happening.


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    Jason Sizto
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