[Users] Avoiding writing one checkpoint file per MPI process

[Lorenzo Ennoggi]

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 CarpetIOHDF5::user_MPIIO  reduces
the peak in the amount of data written to disk at the same time (which was
the actual issue).

Thank you very much Roland,
Lorenzo

On Tue, Nov 1, 2022, 23:59 Lorenzo Ennoggi <lorenzo.ennoggi at gmail.com>
wrote:

> Hi Erik,
> thank you very much for getting back to me. I'll have a look a that and
> try to test it.
>
> Thanks again for your help,
> Lorenzo
>
> On Tue, Nov 1, 2022, 13:49 Erik Schnetter <schnetter at gmail.com> wrote:
>
>> Lorenzo
>>
>> The thorn `Carpet/CarpetSimulationIO` can write N output files on M
>> processes, and uses an efficient mechanism to map in between. That is,
>> it uses the high-speed interconnect instead of disk I/O to exchange
>> data.
>>
>> This thorn is, to my knowledge, not used in production, so you'd want
>> to test it before you use it. It needs the `SimulationIO` external
>> library.
>>
>> -erik
>>
>> On Thu, Oct 6, 2022 at 12:28 PM Lorenzo Ennoggi
>> <lorenzo.ennoggi at gmail.com> wrote:
>> >
>> > Hello,
>> > 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
>> >
>> > IO::out_mode       = "np"
>> > IO::out_proc_every = 8
>> >
>> > 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?
>> >
>> > Thank you very much,
>> > Lorenzo Ennoggi
>> > _______________________________________________
>> > Users mailing list
>> > Users at einsteintoolkit.org
>> > http://lists.einsteintoolkit.org/mailman/listinfo/users
>>
>>
>>
>> --
>> Erik Schnetter <schnetter at gmail.com>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.einsteintoolkit.org/pipermail/users/attachments/20221102/c32cdfb0/attachment-0001.html