Hi, You can actually attach files, instead of pasting file contents directly.
But anyway, the important parts are here; the matrix and solver you picked,
lstype 3 smtype 7
and roughly the number of dofs we are dealing with here
ndofman 136941 nelem 722279
I'm not sure how you have managed to have a whole 722k elements with only 137k nodes. They would have to overlap?
Secondly you have picked linear solver type 3, petsc. Well in this case, you get the solver you specify by using the petsc command line options.
If you didn't pick anyway, I think the default is CG with incomplete LU precond, which often is a good pick.
What solver works best for you depends on a ton of things, and you have everything PETSc can manage on offer here.
There are algebraic multigrid there, but I have only ever had one case where it outperformed CG and GMRES/MINRES
Naturally, the OS is completely irrelevant.