Re: [netcdfgroup] Wondering about when NetCDF data hits the disk...

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: Re: [netcdfgroup] Wondering about when NetCDF data hits the disk...
• From: Russ Rew <russ@xxxxxxxxxxxxxxxx>
• Date: Wed, 02 Dec 2009 12:23:03 -0700

Hi,

Back in October, Thomas Orgis raised the issue of what happens when
nf90_sync() (or nc_sync() for the C API) is called: 
> ...
> So, perhaps it boils down to this: What kind of syncing is implied in
> nf90_sync()? It is just internal NetCDF buffers to operating system
> buffers, I presume... so there is no call to the C fsync() function in
> NetCDF, for example? Or is there such a call and our NFS (with ZFS
> behind) setup is simply broken? But then, 'sync' on the command line
> works...
> 
> Can someone enlighten me on the caching/synchronization strategy there?

Thanks to Thomas's testing of our proposed fix, we decided that a when a
writing process calls nc_sync() it should result in a call to fsync()
(or _commit() for Windows) to improve the timeliness of writes for other
reading processes.  This fix is in the upcoming 4.1 release.

--Russ

• References:
  • [netcdfgroup] Wondering about when NetCDF data hits the disk...
    • From: Thomas Orgis