Management decided to downscale prod server.
Current size: Standard B16ms (16 vcpus, 64 GiB memory)
Desired size: Standard B8ms (8 vcpus, 32 GiB memory)
CPU is mostly idle (output is from sar -u)
10:20:01 CPU %user %nice %system %iowait %steal %idle
10:30:01 all 15.46 0.00 4.24 0.19 0.00 80.11
10:40:01 all 17.11 0.04 4.21 0.18 0.00 78.47
10:50:01 all 19.29 0.00 4.76 0.52 0.00 75.43
What I'm concerned by, it's the memory:
root@precious-server:~# free -h
total used free shared buff/cache available
Mem: 62G 7.9G 26G 510M 28G 53G
Swap: 0B 0B 0B
It seems I have 53GB available, however free value is only 26GB.
Sar reports 53%-57% is used(%memused field), out of which only ~15%-18% is being committed (%commit field):
10:20:01 kbmemfree kbavail kbmemused %memused kbbuffers kbcached kbcommit %commit kbactive kbinact kbdirty
10:30:01 28.9G 55.2G 33.9G 53.9% 2.6G 19.8G 9.7G 15.4% 24.1G 3.7G 11.5M
10:40:01 27.0G 53.3G 35.8G 57.0% 2.6G 19.8G 11.6G 18.5% 26.0G 3.7G 1.7M
10:50:01 26.8G 53.1G 36.0G 57.3% 2.6G 19.8G 11.8G 18.7% 26.2G 3.7G 4.3M
Grafana, reports only 15% of memory is being used:
So, you see my confusion? free command says I have 53GB available, sar says memory used is 52%, while Grafana says 15% used.
I'm not sure I can do the downscale :)
What are your considerations gentlemen?
