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2964136 - Heap memory fragmentation

Symptom

  • SQL: "HANA_Memory_TopConsumers_TimeSlices" (SAP Note 1969700) gives high value for item "Heap (Fragmentation)".

    Example:

       ;SNAPSHOT_TIME ;KEY_FIGURE ;VALUE_TOTAL ;DETAIL_1 ;VALUE_1 ;PCT_1;
    1 ;2020/08/28 10:00:00;Space used (GB); 100;Heap (Fragmentation); 25; 25;
    2 ;2020/08/28 09:00:00;Space used (GB); 100;Heap (Fragmentation); 25; 25;
    3 ;2020/08/28 08:00:00;Space used (GB); 100;Heap (Fragmentation); 25; 25;

  • SQL: "HANA_Memory_ProcessMemory" (SAP Note 1969700) gives high value for column "FRAG_GB".

    Example:

    -------------------------------------------------------------------------------------------------------
    |HOST |PORT |PAL_GB |ALLOC_GB|HEAP_USED_GB|FREE_GB|FRAG_GB|ALLOC_PCT|HEAP_USED_PCT|FREE_PCT|FRAG_PCT|
    -------------------------------------------------------------------------------------------------------
    |saphana|30003| 176.55| 176.14| 155.34| 0.00| 20.80| 99.77| 87.98| 0.00| 11.78|
    -------------------------------------------------------------------------------------------------------

  • HANA DB trace show high value for "Heap memory fragmentation"

    Example:

    Failed to allocate 2565818396904 byte. ... Heap memory fragmentation: 58% (this value may be high if defragmentation does not help solving the current memory request)

Image /data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental.


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Environment

  • HANA database platform 1.0
  • HANA database platform 2.0

Product

SAP HANA, platform edition all versions

Keywords

OOM, dump, run time, rtedump, Failed to allocate, mm poolallocator , KBA , HAN-DB-PERF , SAP HANA Database Performance , HAN-DB , SAP HANA Database , Problem

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