This doesn´t work with ocfs2 on a drbd-volume.
Unmounting volumes with arecursive script works with any filesystem incl. ocfs2. Your unmount script has to unmount the log dirs first before you unmount the ocfs of course.
Btw. How often do you unmount the /var/www volume (as this would stop all hosting services anyway). I havent done this on my servers within the past 10 years or so.