  We consider the thermodynamics of a charged black hole enclosed in a cavity.
The charge in the cavity and the temperature at the walls are fixed so that we
have a canonical ensemble. We derive the phase structure and stability of black
hole equilibrium states. We compare our results to that of other work which
uses asymptotically anti-de Sitter boundary conditions to define the
thermodynamics. The thermodynamic properties have extensive similarities which
suggest that the idea of AdS holography is more dependent on the existence of
the boundary than on the exact details of asymptotically AdS metrics.
