What is the system disk-space break down and how to lower the disk partition

System disk usage shows multiple file system partition and if disk usage is high, we need to lower the disk usage with the valid cleanup method. 

> show system disk-space
Filesystem      Size  Used Avail Use% Mounted on
/dev/root       3.8G  3.2G  438M  89% /
none            2.5G   56K  2.5G   1% /dev
/dev/mmcblk0p5   12G  7.4G  3.5G  69% /opt/pancfg
/dev/mmcblk0p6  3.8G  2.1G  1.6G  58% /opt/panrepo
tmpfs           2.5G  357M  2.2G  15% /dev/shm
cgroup_root     2.5G     0  2.5G   0% /cgroup
/dev/mmcblk0p8  4.7G  2.7G  1.8G  62% /opt/panlogs
/dev/loop0      111M  5.6M  100M   6% /opt/panlogs/wildfire/tmpfile

> show system disk-space
Filesystem      Size  Used Avail Use% Mounted on
/dev/root       3.8G  3.2G  438M  89% / ---------> system root partition
none            2.5G   56K  2.5G   1% /dev
/dev/mmcblk0p5   12G  7.4G  3.5G  69% /opt/pancfg ---------> PAN config partition 
/dev/mmcblk0p6  3.8G  2.1G  1.6G  58% /opt/panrepo ---------> PAN OS repository partition
tmpfs           2.5G  357M  2.2G  15% /dev/shm
cgroup_root     2.5G     0  2.5G   0% /cgroup
/dev/mmcblk0p8  4.7G  2.7G  1.8G  62% /opt/panlogs ---------> PAN Log related partition
/dev/loop0      111M  5.6M  100M   6% /opt/panlogs/wildfire/tmpfile

• / : system root partition : If the root partition is over 90, lower the disk usage with following CLI "debug software disk-usage cleanup deep threshold 90"
• /opt/pancfg : pan config partition : Delete the saved config and pancfg subdirectory usage, verify the usage with following CLI "show system pancfg-directory-usage"
• /opt/panlogs : pan log related partition :  Lower the disk quota rate or delete the old logs. 
• /opt/panrepo: PAN OS repository partition : Lower the disk space by deleting the old PAN-OS.