Fdisk

Resizing existing disk space on root fs without using gparted.

Increase vmdisk space
In OS as root
sudo fdisk /dev/sda
Command (m for help): p
Command (m for help): d
Command (m for help): d
Command (m for help): n
Command (m for help): t (8e)
Command (m for help): w
(you might need to reboot or lazy unmount umount -l /opt
lsblk
sudo pvresize /dev/sda5 (lvm disk you increased in fdisk)
sudo lvextend -L100G /dev/vg00/opt  (extend whatever patition size you want