[Paraview] Serial & Parallel - Scientific Data

[Léo Pessanha]

Hi Utkarsh, thank you for the detailed explanation =)

I will definitely try out and see the different performances with
compressed/decompressed data.

The data types are *Structured Grid*, *Structured Points *and* Rectilinear
Grid. *All of them are written in VTK 2.0 version.

When loading in 2 ranks the data is loaded only in 1 rank (ID 0)
consequently having only one color.


Em qui, 19 de abr de 2018 22:29, Utkarsh Ayachit <
utkarsh.ayachit at kitware.com> escreveu:

> The options presented when saving data:
>>
>
>> - Data Mode: ASCII | BINARY | APPENDED
>> - Encode Appended Data: TRUE | FALSE
>> - Compressor Type:  NONE | ZLIB
>>
>> *What do the mean and how they affect performance?*
>>
>
> These determine how the binary data (your arrays, point coordinates etc)
> is saved in the file. ASCII is not to be used to anything but small dataset
> for debugging. BINARY saves the data as binary, however it still needs to
> encode it (using base64) so that the XML can be parsed correctly.
> Generally, you want to pick APPENDED (where the binary data is added at the
> end of the XML header(ish) and then can be saved as raw binary dump without
> any encoding. No encoding implies you can't easily look at the file in a
> ASCII text editor, but will be easier to write and read since neither needs
> to do any processing to convert the binary data. For appended APPENDED or
> BINARY mode, compressor type allows you to pick a compression technique to
> use. This minimizes file size but adds computing cost of compressing
> /decompressing. It's a trade off between reading more from  the disk or
> spending more time decompressing it after reading form disk. Generally,
> reading form disk is slower, so you may still be better off compressing.
> 5.5 offer better compression options like LZ4 & LZMA which may be worth
> exploring too.
>
> Before I answer your other questions, what type of data is this? Image
> data? Unstructured grid? When you load it on 2 ranks, if you color your
> surface by vtkProcessId, is it being read in as paritioned across two ranks
> or all of the data is on rank 0?
>
> Utkarsh
>
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