# Using WriteVTK to write DiffEq sol to disk during timestepping

**URL:** <https://discourse.julialang.org/t/using-writevtk-to-write-diffeq-sol-to-disk-during-timestepping/104517>\
**Category:** Modelling & Simulations\
**Tags:** diffeq\
**Created:** [October 3, 2023, 12:21am UTC](https://discourse.julialang.org/t/using-writevtk-to-write-diffeq-sol-to-disk-during-timestepping/104517 "2023-10-03T00:21:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jarias9](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jarias9](https://discourse.julialang.org/u/jarias9)\
**Post date:** [October 3, 2023, 12:21am UTC](https://discourse.julialang.org/t/using-writevtk-to-write-diffeq-sol-to-disk-during-timestepping/104517/1 "2023-10-03T00:21:11Z")

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Just had a quick question regarding alternative saving behavior for DiffEq. I was wondering if there was a way to write all solution data directly to disk with WriteVTK as timestepping advances instead of having all of my saved time steps in the sol object and then writing to disk. The reason being that I would like to run long term simulations in a cluster environment and storing all the solutions in RAM before writing to disk is very memory intensive, even with using saveat. I was thinking perhaps a callback function could achieve this but I am not familiar enough with using callbacks to know.

Thanks!

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [October 3, 2023, 9:57pm UTC](https://discourse.julialang.org/t/using-writevtk-to-write-diffeq-sol-to-disk-during-timestepping/104517/2 "2023-10-03T21:57:24Z")

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Just do `save_on=false` and use a `SavingCallback` which calls WriteVTK.