As you can see, most of those are in use even during our
  periods of "light" usage.
At Mike's request since "it isn't true now.  It will probably be true
again, but it will take awhile..."

That is when more than a fixed threshold of nodes (0.05 for now) are
in an invalid state for any particular class (ie "pc3000s", "d710s",
etc) only invalid that class for the time period, instead of all the
plot data.

Along the way fix various bugs with handling NaN (how invalid states
are flagged).

to avoid running out of memory.

problems.  When someone other than we does an install.

setup, see http://users.emulab.net/trac/emulab/wiki/NodeUsageInstall.

beleive we really have this stuff set up to run well at other sites.

table.  Right now Utah testbed only.