The way how to reset or change forgotten root password on LINUX platform.
1. reset system and open single user mod by changing init option
2. remount root directory and make it writable
# mount -o remount,rw /
3. in case we use separated filesystem for usr we need it mount at first
# cat /etc/fstab # mount /dev/vg00/lv_usr /usr
4. at last we can change root paswword