  We present preliminary results for the D_s meson spectroscopy study on the
2+1 flavour domain wall fermion lattice configurations, generated with the
Iwasaki gauge action at beta=2.13 by the RBC-UKQCD collaboration. The
simulations are on 16^3\times32 lattice with L_s=16. We consider the charm
quark propagating as an overlap fermion at fixed lattice spacing. The
dispersion relation and mass splittings are evaluated.
