NAS info sensor via SSH

I would like to monitor some NAS info with HA through SSH. I finally got the authentication working and I am now having trouble setting up the sensor. I’m not sure exactly what command/syntax to use after getting connected. I’ve seen a couple of different examples but how do I find out exactly what it is for my HDD?

df | sed -n '/HD_a2/s/ \+/ /gp' | cut -d' ' -f 2

df -h | awk '/\/dev\/disk3s2/ {print $5}' | grep -o -E '[0-9]+'"

Thanks so much!

I got it!

df /dev/md2 | awk 'FNR == 2 {print $5}'

Thanks everyone!