Suppose I am running on 12 processors, and I have a vector "v" of size 36 partitioned over the first 4. v still uses the PETSC_COMM_WORLD, so it has a layout of (9, 9, 9, 9, 0, 0, ..., 0). Now, I would like to repartition it over all 12 processors, so that the layout becomes (3, 3, 3, ..., 3). I've been trying to use VecScatter to do this, but I'm not sure what IndexSets to use for the sender and receiver. The result I am trying to achieve is this: Assume the vector is v = <0, 1, 2, ..., 35> Start Finish Proc | Entries Proc | Entries 0 | 0,...,8 0 | 0, 1, 2 1 | 9,...,17 1 | 3, 4, 5 2 | 18,...,26 2 | 6, 7, 8 3 | 27,...,35 3 | 9, 10, 11 4 | None 4 | 12, 13, 14 5 | None 5 | 15, 16, 17 6 | None 6 | 18, 19, 20 7 | None 7 | 21, 22, 23 8 | None 8 | 24, 25, 26 9 | None 9 | 27, 28, 29 10 | None 10 | 30, 31, 32 11 | None 11 | 33, 34, 35 Appreciate any help you can provide on this. Thanks, Sreeram