VDS RAM Usage Graph?

Question

linux

Regular VDS - Debian, Apache+nginx, php, mysql, ISPmanager
RAM usage graph (red)

Somewhat strange )) How to diagnose what exactly (which site) consumes it and how does it clear itself if I do nothing?

Answer 1

If your apache writes a log of the request execution time, then look there, mb there is something to catch on.
In general, put zabbix .

Answer 2

If you decide with crutches - reset the result of the command "ps -xau | sort -nk5 -r" to the log every 5 minutes by cron, with the fixation of the time when the command is running. It will write to you in the log a list of processes sorted by the VSZ (virtual size) field in reverse order (the largest ones are at the beginning of the list). So look who's naughty there.
NB: The syntax of the command is given for FreeBSD, on Linux the keys may differ.

Answer 3

I advise munin