<div dir="auto">Also, I have just realized I missed the last email from Roland. I'll also have a look at branch rhaas/mpiio of Carpet and try to setup a test on few nodes to see if/how much using the parameter <span style="font-size:12.8px">CarpetIOHDF5::user_MPIIO</span> reduces the peak in the amount of data written to disk at the same time (which was the actual issue).<div dir="auto"><br></div><div dir="auto">Thank you very much Roland,</div><div dir="auto">Lorenzo</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 1, 2022, 23:59 Lorenzo Ennoggi <<a href="mailto:lorenzo.ennoggi@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">lorenzo.ennoggi@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto">Hi Erik,<div dir="auto">thank you very much for getting back to me. I'll have a look a that and try to test it.</div><div dir="auto"><br></div><div dir="auto">Thanks again for your help,</div><div dir="auto">Lorenzo</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 1, 2022, 13:49 Erik Schnetter <<a href="mailto:schnetter@gmail.com" rel="noreferrer noreferrer noreferrer noreferrer noreferrer noreferrer noreferrer" target="_blank">schnetter@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Lorenzo<br>
<br>
The thorn `Carpet/CarpetSimulationIO` can write N output files on M<br>
processes, and uses an efficient mechanism to map in between. That is,<br>
it uses the high-speed interconnect instead of disk I/O to exchange<br>
data.<br>
<br>
This thorn is, to my knowledge, not used in production, so you'd want<br>
to test it before you use it. It needs the `SimulationIO` external<br>
library.<br>
<br>
-erik<br>
<br>
On Thu, Oct 6, 2022 at 12:28 PM Lorenzo Ennoggi<br>
<<a href="mailto:lorenzo.ennoggi@gmail.com" rel="noreferrer noreferrer noreferrer noreferrer noreferrer noreferrer noreferrer noreferrer" target="_blank">lorenzo.ennoggi@gmail.com</a>> wrote:<br>
><br>
> Hello,<br>
> In order to avoid stressing the filesystem on the cluster I'm running on, I was suggested to avoid writing one output/checkpoint file per MPI process and instead collecting data from multiple processes before outputting/checkpointing happens. I found the combination of parameters<br>
><br>
> IO::out_mode = "np"<br>
> IO::out_proc_every = 8<br>
><br>
> does the job for output files, but I still have one checkpoint file per process. Is there a similar parameter, or combination of parameters, which can be used for checkpoint files?<br>
><br>
> Thank you very much,<br>
> Lorenzo Ennoggi<br>
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