Symptoms

There is a difference between real RAM usage in container and the usage reported by OACI: for example, OACI can show 5 Mb memory usage in a Linux container, while free utility from inside the container shows correct memory usage.

Cause

Since OACI 5.5 update 8 and PCS 6 update 8 memory usage is reported as

usage = guest.ram.usage - guest.ram.cached

These values come from prlctl statistics tool:

# prlctl statistics 101
    guest.ram.usage:        53
    guest.ram.cached:       47

guest.ram.cached is a Cached value in /proc/meminfo from inside the virtual environment, and it includes shared memory as well as usual caches. If a virtual environment actively uses Shmem (for example, PostgreSQL instance is running inside), OACI will report memory usage incorrectly.

Resolution

OACI memory calculation will be redesigned in scope of feature request POA-91401. Please contact your TAM/PTA to trace the status of the issue.

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