# Transient aware extractor
**URL:** https://discourse.paraview.org/t/transient-aware-extractor/13680
**Category:** In Situ Support
**Created:** [January 11, 2024, 8:53pm UTC](https://discourse.paraview.org/t/transient-aware-extractor/13680 "2024-01-11T20:53:11Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Juan\_Jose\_Casafranca](https://discourse.paraview.org/u/Juan_Jose_Casafranca)
#### Post date: [January 11, 2024, 8:53pm UTC](https://discourse.paraview.org/t/transient-aware-extractor/13680/1 "2024-01-11T20:53:11Z")
I am preparing my simulation code to use catalyst. I use the multimesh protocol representing a hierarchy of vtkUnstructuredGrid.
I have two use cases:
First, I want to perform live visualization, as I sometimes debug the simulation code while I am watching the simulation results. This use case works fine.
I also want to store my simulation, from start to finish, in a simulation file. In this simulation file I just store the raw geometry data. Sometime I let the simulation running and I go away. When I come back, I want to load a file and see if everything was correct. For that, I would prefer to have a single file with all the timesteps.
Is there any extractor that can save the data for all the timesteps so I can later analyze it?
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### Author:  [@nicolas.vuaille](https://discourse.paraview.org/u/nicolas.vuaille)
#### Post date: [January 12, 2024, 9:55am UTC](https://discourse.paraview.org/t/transient-aware-extractor/13680/2 "2024-01-12T09:55:57Z")
Hi !
> [@Juan\_Jose\_Casafranca](#):
>
> This use case works fine.
Nice 🙂
> [@Juan\_Jose\_Casafranca](#):
>
> I would prefer to have a single file
This does not exists as of now but it is in our roadmap!
A lot of work are on the way with the VTKHDF file format ([VTK File Formats - VTK documentation](https://docs.vtk.org/en/latest/design_documents/VTKFileFormats.html#vtkhdf-file-format)) that is the new standard way to read/write data in VTK (and thus in ParaView and catalyst). One of the next step is exactly to support transient write in a single file.
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### Author:  [@Juan\_Jose\_Casafranca](https://discourse.paraview.org/u/Juan_Jose_Casafranca)
#### Post date: [January 12, 2024, 10:08am UTC](https://discourse.paraview.org/t/transient-aware-extractor/13680/3 "2024-01-12T10:08:08Z")
Thats okay. For now, Ill write the data to VTKHDF when I am sending it to catalyst