Perhaps I'm missing something obvious, but DA refine/coarsen with stencil_width=0 for nproc>1 is failing, see the example below [dalcinl@nikola petsc4py-dev]$ cat test-da-rc.py import sys, petsc4py petsc4py.init(sys.argv) from petsc4py import PETSc OptDB = PETSc.Options() n = OptDB.getInt('n', 100) da = PETSc.DA().create([n], dof=1, stencil_width=0) rda = da.refine() cda = da.coarsen() [dalcinl@nikola petsc4py-dev]$ mpiexec -n 1 python test-da-rc.py [dalcinl@nikola petsc4py-dev]$ mpiexec -n 2 python test-da-rc.py Traceback (most recent call last): File "test-da-rc.py", line 10, in <module> rda = da.refine() Traceback (most recent call last): File "test-da-rc.py", line 10, in <module> rda = da.refine() File "DA.pyx", line 408, in petsc4py.PETSc.DA.refine (src/petsc4py.PETSc.c:115026) File "DA.pyx", line 408, in petsc4py.PETSc.DA.refine (src/petsc4py.PETSc.c:115026) petsc4py.PETSc.Errorpetsc4py.PETSc.Error: error code 60 [0] DMRefine() line 541 in /usr/local/petsc/dev/src/dm/interface/dm.c [0] DMRefine_DA() line 770 in /usr/local/petsc/dev/src/dm/impls/da/da.c [0] DMDARefineOwnershipRanges() line 668 in /usr/local/petsc/dev/src/dm/impls/da/da.c [0] Nonconforming object sizes [0] Could not find a compatible refined ownership range : error code 60 [1] DMRefine() line 541 in /usr/local/petsc/dev/src/dm/interface/dm.c [1] DMRefine_DA() line 770 in /usr/local/petsc/dev/src/dm/impls/da/da.c [1] DMDARefineOwnershipRanges() line 668 in /usr/local/petsc/dev/src/dm/impls/da/da.c [1] Nonconforming object sizes [1] Could not find a compatible refined ownership range -- Lisandro Dalcin --------------- CIMEC (INTEC/CONICET-UNL) Predio CONICET-Santa Fe Colectora RN 168 Km 472, Paraje El Pozo 3000 Santa Fe, Argentina Tel: +54-342-4511594 (ext 1011) Tel/Fax: +54-342-4511169