What kind of problems are you solving? Running for a Krylov method for tens of thousands of iterations is very rarely recommended.
Regarding storage, it's significantly more expensive to store the Krylov basis (even when it's a recurrence) than the current approximation. Some methods require some work to compute the current approximation. Anyway, you can use a KSPMonitor to write checkpoints at whatever interval you like. In case of a crash, use VecLoad() to read in the checkpoint file and use KSPSetInitialGuessNonzero() to make it be used as an initial guess. Sal Am <tempoho...@gmail.com> writes: > This is how I run it: > > -ksp_type bcgs -pc_type gamg -mattransposematmult_via scalable > -build_twosided allreduce -ksp_monitor_true_residual > -ksp_monitor_if_not_converged -log_view -ksp_max_it 100000 -ksp_rtol 1.0e-7 > > so BCGS with GAMG as preconditioner. I am guessing writing at every > timestep would be expensive, maybe every hour? I am not sure what would be > a good number here if the simulations lasts more than a day. > > > > On Mon, Feb 18, 2019 at 4:10 PM Jed Brown <j...@jedbrown.org> wrote: > >> What kind of solver are you using and how often do you want to write? >> >> Sal Am via petsc-users <petsc-users@mcs.anl.gov> writes: >> >> > Is there a function/command line option to save the solution as it is >> > solving (and read in the file from where it crashed and keep iterating >> from >> > there perhaps)? >> > Had a seg fault and all the results until that point seems to have been >> > lost. >>