$ cd src/dm/da/examples/tests $ make ex3 $ mpiexec -n 5 ./ex3 -M 8 The issue is that the partition [0,2,4,6,7,8] is refined to [0,3,6,9,12,15]. Now on rank 3, the start indices (6 and 9) don't line up (because 9/2=4 < 6-1). I'm about to push a patch for this that creates and always uses lx,ly,lz for refinement so that the subdomains are always nested. The downside of this is that when the coarse level is imbalanced (not a serious problem), all refinements will preserve the coarse fractional imbalance, which may be a big problem on the fine meshes.
It is probably not hard to redistribute lx,ly,lz within the constraints that DAGetInterpolation has to work, so you can't move a subdomain interface by more than one coarse stencil width. But I'm not sure that any redistribution is always desirable (especially if the user used DASetVertexDivision). Jed
