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Memory Utilization Discrepancies in Linux

edited Jan 30, 2023 2:26AM in Linux Operating System (MOSC) 6 commentsAnswered

Hi,

Oracle Linux Server release 8.6

Oracle database version - 19.15.0.0.0

Having some concerns related to memory utilization in linux.

Just want to understand why there is a discrepancy with memory utilization which shows up in sar,free and nmon command/tool.


$ free -h

        total    used    free   shared buff/cache  available

Mem:      39Gi    20Gi    10Gi    520Mi    7.5Gi    17Gi

Swap:     15Gi    789Mi    15Gi


sar -r

12:00:00 AM kbmemfree  kbavail kbmemused %memused kbbuffers kbcached  

12:10:00 AM 11408856  18279672 29568712   72.16   2273380  4621608  

12:20:00 AM 11442760  18314588 29534808   72.08   2273820  4622172  

12:30:00 AM 11426300  18299556 29551268   72.12    2274276  4623252  

12:40:00 AM 11426120  18300896 29551448   72.12   2274752  4623760  

12:50:00 AM 11442288  18317608 29535280   72.08   2275164  4623884  

01:00:00 AM 11411056  18287800 29566512   72.15   2275572  4624808  


Free command shows 20GB is used or 17GB available however SAR is showing 29GB is used(72%)

which one is correct. Please assist me on this. Thank you !

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