@peterleinchen

If I do "du -h /usr/lib" I get 201.5M. If I do "du -xh /usr/lib" I get 141.4M.

Doing a diff on both outputs it is clear that "-xh" omits/ignores the 3 directories that are bind-mounted on /usr/lib, i.e. python2.5, pyshared and python-support.

You are probably doing "du -xsh /usr/lib/*" (note the "*") which is effectively overriding the "-x" by telling du explicitly to calculate the size of every directory under /usr/lib/, that is, including those [r]bind-mounted.