Re: [netcdfgroup] Issue that permission error occurs according to filetype when using parallel netcdf

• To: Kihang Youn <kyoun@xxxxxxxxxx>
• Subject: Re: [netcdfgroup] Issue that permission error occurs according to filetype when using parallel netcdf
• From: Wei-Keng Liao <wkliao@xxxxxxxxxxxxxxxx>
• Date: Sat, 20 Feb 2021 03:51:07 +0000
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To use parallel I/O feature of NetCDF F90, you have to call
   nf90_create(FILE_NAME, IOR(NF90_NETCDF4, NF90_CLOBBER), ncid, &
               comm = MPI_COMM_WORLD, info = MPI_INFO_NULL)

To use sequential I/O feature of NetCDF F90, you have to call
   nf90_create(FILE_NAME, IOR(NF90_NETCDF4, NF90_CLOBBER), ncid)

NF90_MPIIO no longer takes effect when the NetCDF Fortran library is built with
recent NetCDF C library. That flag's corresponding flag in C, NC_MPIIO, has
become obsolete since C version 4.6.2.

The error "permission denied" may be because the file you are trying to create
has already existed. Without NF90_CLOBBER, you cannot create an 
already-existing file.

If you provided some code fragments, it helps isolate the problem.

Wei-keng

> On Feb 18, 2021, at 9:03 AM, Kihang Youn <kyoun@xxxxxxxxxx> wrote:
> 
> 
> Hi All,
> 
> I have some questions about netcdf file format with parallel netcdf library.
> 
> First, I was wondering the priority of IOR in nf_create function. 
> For examples, how is the priority of the three values determined in the 
> command below?
> I want to know clearly whether the 3 variables already have priority or 
> whether it depends on the order or position of the IOR.
> IOR(NF90_MPIIO, IOR(NF90_NETCDF4, NF90_CLOBBER))
> 
> Second, if I use parallel io and NF90_NETCDF4 is used, permission denied 
> occurs, but it does not occur in NF90_CLOBBER or NF90_MPIIO.
> How to understand in this case?
> 1) NF90_CLOBBER was written sequentially without any problems.
> 2) NF90_MPIIO was written parallelly without any problems.
> 3) NF90_NETCDF4 is tried as parallel, but is the problem caused by the wrong 
> file type?
> 
> Best Regards,
> Kihang
> 
> Kihang Youn(윤기항) - Application Analyst | Lenovo DCG Professional Services
> Mobile: +82-10-9374-9396
> E-mail: kyoun@xxxxxxxxxx
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• References:
  • [netcdfgroup] Issue that permission error occurs according to filetype when using parallel netcdf
    • From: Kihang Youn
  • [netcdfgroup] Issue that permission error occurs according to filetype when using parallel netcdf
    • From: Kihang Youn