Lemme start with my system spec: CentOS 7.6 Virtualmin 6.06 Webmin 1.900 Usermin 1.751 23.88 GB Ram 2.67 TB HDD Kernel and CPU Linux 3.10.0-957.10.1.el7.x86_64 on x86_64
Additions: CSF + LFD IPv6 /64 block
I don't know about anyone else, but day after day I could watch my cached memory grow and grow. Each day the dial percentage would creep up 2 to 5%. I'd never let it get above 20% before restarting it (bind, fail2ban, mysql, and polkitd are my top offenders). So I started looking on the webs (like, who doesn't) and came across something that I wanted to share.
Now, I have a cronjob running at midnight everyday as root with this command;
sync; echo 1 > /proc/sys/vm/drop_caches && swapoff -a && swapon -a
Came across it here -> How to Clear RAM Memory Cache, Buffer and Swap Space on Linux