Ubuntu – How to log memory usage per minute on Ubuntu Server

You can use

cat /proc/loadavg

That gives you the 3 load average numbers for the period 1, 5, and 15 minutes.

Then the number of currently running processes and then the pid of the last called process.

I don't know what you mean with the median and deviation values.

But hopefully this is a start for you.

cat /proc/meminfo

gives you memory stats.

The /proc directory could give you more infos for your needs. Just cat /proc/xxxx the file you are interested in.

cat

is just a programm to show the contents of a file to your termial. Jo can use your javaprogramm or whatever to read those files and send the values to your database.

ZFS will cache data and metadata so given a lot of free memory this will be used by ZFS. When memory pressure starts to occur (for example, loading programs that require lots of pages) the cached data will be evicted. If you have lots of free memory it will be used as cache until it is required.

You can use the arc_summary tool to see the resources used by the ZFS ARC (adaptive replacement cache)