Hi, I am trying to solve a Poisson equation on this grid: Nx = 2501 Ny = 3401 Nz = 1601 I received this error: [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: Overflow in integer operation: http://www.mcs.anl.gov/petsc/documentation/faq.html#64-bit-indices [0]PETSC ERROR: Mesh of 2501 by 3401 by 1 (dof) is too large for 32 bit indices [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting. [0]PETSC ERROR: Petsc Release Version 3.8.3, Dec, 09, 2017 [0]PETSC ERROR: /marconi_scratch/userexternal/pminelli/PIC3D/2500_3400_1600/./PIC_3D on a arch-linux2-c-opt named r129c09s02 by pminelli Tu e May 26 20:16:34 2020 [0]PETSC ERROR: Configure options --prefix=/cineca/prod/opt/libraries/petsc/3.8.3/intelmpi--2018--binary CC=mpiicc FC=mpiifort CXX=mpiicpc F77=mpiifort F90=mpiifort --with-debugging=0 --with-blaslapack-dir=/cineca/prod/opt/compilers/intel/pe-xe-2018/binary/mkl --with-fortran=1 --with-fortran-interfaces=1 --with-cmake-dir=/cineca/prod/opt/tools/cmake/3.5.2/none --with-mpi-dir=/cineca/prod/opt/compilers/intel/pe-xe- 2018/binary/impi/2018.4.274 --download-scalapack --download-mumps=yes --download-hypre --download-superlu_dist --download-parmetis --downlo ad-metis [0]PETSC ERROR: #1 DMSetUp_DA_3D() line 218 in /marconi/prod/build/libraries/petsc/3.8.3/intelmpi--2018--binary/BA_WORK/petsc-3.8.3/src/dm/ impls/da/da3.c [0]PETSC ERROR: #2 DMSetUp_DA() line 25 in /marconi/prod/build/libraries/petsc/3.8.3/intelmpi--2018--binary/BA_WORK/petsc-3.8.3/src/dm/impl s/da/dareg.c [0]PETSC ERROR: #3 DMSetUp() line 720 in /marconi/prod/build/libraries/petsc/3.8.3/intelmpi--2018--binary/BA_WORK/petsc-3.8.3/src/dm/interf ace/dm.c forrtl: error (76): Abort trap signal I am on an HPC facility and after I loaded PETSC module, I have seen that it is configured with INTEGER size = 32 I solve my problem with these options and it works perfectly with smaller grids: -dm_mat_type hypre -pc_type hypre -pc_hypre_type boomeramg -pc_hypre_boomeramg_relax_type_all SOR/Jacobi -pc_hypre_boomeramg_coarsen_type PMIS -pc_hypre_boomeramg_interp_type FF1 -ksp_type richardson Is it possible to overcome this if I ask them to install a version with INTEGER SIZE = 64? Alternatively, is it possible to overcome this using intel compiler options? Thanks in advance Pierpaolo Minelli