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<p>hi Matt<br>
</p>
<div class="moz-cite-prefix">On 2/10/24 1:01 am, Matthew Knepley
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAMYG4GkNZ=sV1DmJs45kzuQHx15VR2ssymRguPp2C0v7LvfjjQ@mail.gmail.com">
<div dir="ltr">
<div dir="ltr">On Mon, Sep 30, 2024 at 10:15 PM Adrian Croucher
<<a href="mailto:a.croucher@auckland.ac.nz" moz-do-not-send="true" class="moz-txt-link-freetext">a.croucher@auckland.ac.nz</a>>
wrote:<br>
</div>
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">hi,
I am testing my (Fortran) code on PETSc 3.22 and have got it
to <br>
build. However I am getting some unusual new behaviour when
I write an <br>
IS to an HDF5 file using ISView().<br>
<br>
The attached minimal example shows the issue. It creates a
simple <br>
10-element IS and writes it to HDF5. With previous versions
of PETSc <br>
this would give me a 10x1 dataset containing the values 0 -
9, as expected.<br>
<br>
When I run it with PETSc 3.22 (in serial), I again get the
expected <br>
values written on stdout, so it looks like the IS itself is
correct. But <br>
in the HDF5 file I get a 1x3 dataset containing the values
(10,1,0).<br>
<br>
Has something changed here?<br>
</blockquote>
<div><br>
</div>
<div>Yes. We now compress IS data sets by default. You can
turn it off using -is_view_compress 0. I am not sure</div>
<div>what the best way to manage this is, but it makes a huge
difference in file size for checkpointing.</div>
</div>
</div>
</blockquote>
<p>Thanks. I guess that's fine if it's being read back in by PETSc,
but I have users with non-PETSc post-processing codes needing to
read my output, and they aren't going to know what to do with
these compressed datasets. I only write one IS at the start of
each simulation, so it's a negligible contribution to the file
size.</p>
<p>So I think I will need to disable the compression in my code. Is
there a function call I can use to do that, to make sure it's
always done without users needing to pass -is_view_compress 0?</p>
<p>- Adrian<br>
</p>
<pre class="moz-signature" cols="72">--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
Waipapa Taumata Rau / University of Auckland, New Zealand
email: <a class="moz-txt-link-abbreviated" href="mailto:a.croucher@auckland.ac.nz">a.croucher@auckland.ac.nz</a>
tel: +64 (0)9 923 4611</pre>
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