Michael,

The Q OCC command reports the number of objects that have data stored
in a storage pool.  The report shows occupancy by storage pool.  Since
each storage pool is associated with a device class, you can determine
how much disk or tape space is being used by a given client.  Each object
being stored will use a different amount of db space, depending on whether
it has data associated with it, the type of media that data is stored on,
and various other factors.  Also, the metadata stored in the db is compressed
so it's almost impossible to estimate the actual db space used by a given
client.

So how can you use the available information for a reasonable charge-back?
I don't have a really good answer, but here are some things to consider.

You can make a gross estimate of the db space used by the number of objects
  reported in Q OCC to be about 1-2% of the used space reported by Q OCC.  This
  is a pretty rough estimate, but it may be good enough to take into account
  the number of non-data objects.

Since the total number of db pages in use is reported by Q DB, you could
  devise an algorithm to spread the cost of those pages across your registered
  clients.  This cost could be weighted proportionally to the number of objects
  stored as reported by Q OCC.

While these suggestions don't take into account the extreme case you mention,
they are reasonable estimates for spreading the cost of db space across your
client base.

Wayne Hineman