Update / Modify the logic for "Virtual Memory in use" alert in DMC.

Proposed Enhancement Description (DB2 DMC – Virtual Memory In Use Alert)

DB2 DMC currently calculates VIRTUAL_MEM_IN_USE using the following query:

SELECT MEMBER, MEMORY_SWAP_TOTAL, MEMORY_SWAP_FREE, MEMORY_TOTAL, MEMORY_FREE, CAST(( CASE WHEN (MEMORY_SWAP_TOTAL + MEMORY_TOTAL)=0 OR (MEMORY_SWAP_TOTAL + MEMORY_TOTAL) IS NULL THEN NULL ELSE ( (CAST(MEMORY_SWAP_TOTAL AS DOUBLE) - CAST(MEMORY_SWAP_FREE AS DOUBLE) + CAST(MEMORY_TOTAL AS DOUBLE) - CAST(MEMORY_FREE AS DOUBLE)) / (CAST(MEMORY_SWAP_TOTAL AS DOUBLE) + CAST(MEMORY_TOTAL AS DOUBLE)) ) * 100.0 END ) AS DECIMAL(5,2)) AS VIRTMEMINUSE_PERCENT FROM TABLE(SYSPROC.ENV_GET_SYSTEM_RESOURCES()) WITH UR;

This logic appears outdated and no longer reflects how modern Linux kernels report memory usage.
From RHEL 7/8 onward, the free command and /proc/meminfo introduced Available Memory, which provides a far more accurate representation of true usable memory than the older free field used in RHEL 6.

Example (RHEL 8):
           total used free shared buff/cache available 

Mem: 1.5Ti 52Gi 51Gi 468Gi 1.4Ti 981Gi

However, the table function SYSPROC.ENV_GET_SYSTEM_RESOURCES() exposes only:
MEMORY_TOTAL, MEMORY_FREE, MEMORY_SWAP_TOTAL, MEMORY_SWAP_FREE, VIRTUAL_MEM_TOTAL, VIRTUAL_MEM_RESERVED, VIRTUAL_MEM_FREE

There is no column for Available Memory, meaning DMC cannot compute memory utilisation in a way that aligns with modern OS reporting (buffers, cache, reclaimable memory, etc.).

As a result, the current DMC virtual memory alert often produces misleading utilisation percentages on newer Linux versions. This behaviour has also been confirmed by IBM Support in case TS020869118.

Request

Please update the DMC memory utilisation logic to use a calculation aligned with modern Linux “available memory” semantics, or extend SYSPROC.ENV_GET_SYSTEM_RESOURCES() to include an AVAILABLE_MEMORY metric so DMC can derive accurate memory‑in‑use values across current OS platforms. It would help all the DMC users to receive accurate alert messages.