FILL and NOFILL

[John Michalakes]

Thanks for the response.   Just to be clear, it is good news that pNetCDF
does not have fill mode.  I'm in the process of adding an option to WRF when
writing using serial NetCDF and I was wondering if it would be necessary to
add such an option to the pNetCDF interface in WRF as well.  I'm very happy
with your answer, thanks.   -John 

-----Original Message-----
From: Wei-keng Liao [mailto:wkliao at eecs.northwestern.edu] 
Sent: Monday, February 24, 2014 2:45 PM
To: John Michalakes
Cc: parallel-netcdf at lists.mcs.anl.gov
Subject: Re: FILL and NOFILL

Hi, John,

PnetCDF does not support fill mode. (It is on the wish list I guess.)

As pointed out from the URL in your email, enabling fill mode
requires "duplicate writes" which fill in the variables with fill
values before overwrite the variables later with user's data.
The pitfall is just poor performance.

Wei-keng

On Feb 24, 2014, at 3:36 PM, John Michalakes wrote:

> That's good. Thanks, -John
>  
> From: parallel-netcdf-bounces at lists.mcs.anl.gov
[mailto:parallel-netcdf-bounces at lists.mcs.anl.gov] On Behalf Of Jim Edwards
> Sent: Monday, February 24, 2014 1:20 PM
> To: John Michalakes
> Cc: parallel-netcdf at lists.mcs.anl.gov
> Subject: Re: FILL and NOFILL
>  
> No, pnetcdf does not use fill mode.
>  
> 
> On Mon, Feb 24, 2014 at 10:58 AM, John Michalakes
<john.michalakes at noaa.gov> wrote:
> Does parallel netcdf have an equivalent to nc_set_fill?
>  
>
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-c/nc_005fset_005ffil
l.html
>  
> If so, what is the default mode, FILL or NOFILL , and are there
performance benefits for using NOFILL as there are with serial NetCDF?  Any
pitfalls?
>  
> Thanks,
>  
> John
> 
> 
> 
> --
> Jim Edwards
>