Make sure you have met the prerequisites listed on "Prerequisites".
Unmount all the file systems listed in the /etc/vfstab file.
All systems that are unmounted, except those that are busy.
For the file systems that were busy and not unmounted, make them available to be unmounted as described in "How to Stop All Processes Accessing a File System".
Repeat Step 2 as needed until all file systems are unmounted.