  We study preconditioning techniques for discontinuous Galerkin
discretizations of isotropic linear elasticity problems in primal
(displacement) formulation. We propose subspace correction methods based on a
splitting of the vector valued piecewise linear discontinuous finite element
space, that are optimal with respect to the mesh size and the Lame parameters.
The pure displacement, the mixed and the traction free problems are discussed
in detail. We present a convergence analysis of the proposed preconditioners
and include numerical examples that validate the theory and assess the
performance of the preconditioners.
