fc4 install with /usr as read only

[list user]

Hi all,

Still experimenting with xen and lvm on fc4.

I've created a mount point, /usr, that is read only, thinking more than 
one xen domain could use it.

Even though I've never used it this way, I always (mistakenly?) thought 
that /usr could be read only.  I've been turning off most services one 
by one, and keep making it further, but have yet to successfully boot 
completely.

Rather than a clean install, I created it with lvcreate vg0/usr, 
mkfs.ext3, mount vg0/usr /mnt, cp -a /usr /mnt, then edited fstab to 
create a /usr mount with standard defaults except rw as ro.

I'm not convinced yet that that was the correct way to do this, or 
whether my original assumption that /usr could exist as a "read only" 
directory was correct.

Can anybody comment on my approach to this or recommend another approach 
that might yield success?

Thanks to all for your time and thoughts.

:m)