Note that this tip applies to Solaris 7 and 8.
Have you ever tried to unmount a filesystem and found that there is something blocking it?
To forcefully unmount a busy filessystem in Solaris 7, proceed as follows:
lockfs /mount_point
fuser -kc /mount_point
umount /mount_point
And for Solaris 8…
umount -f /mount_point
Be very careful. Using this option can cause data loss for open files: programs which access files after the filesystem has been unmounted will get an error (EIO).