netcdf question

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: netcdf question
• From: sloan@xxxxxxxxxxxxxxxxxxx (Quinn Sloan)
• Date: Mon, 27 Feb 1995 17:58:30 EST

Hello,

I am a graduate student in oceanography using the
netcdf library for some numerical modeling purposes,
and I have a question about netcdf and communications.

I typically write out a couple of meg's of data at the 
beginning of the numerical computation, and this 
normally takes about a minute or so if the code is 
executing on the same cpu as the disk that is being written
to.  But if the cpu and disk are different machines,
then it takes over 30 minutes to perform the same writing.
I am using two sparc 10's in this case running SunOS
release 4.1.3 and NFS and f77.  The times that I've
given are really approximate, but from my experience,
the ratio of (time using one machine) / (time using 2 machines)
is significantly greater than the ratio
(disk write) / (ethernet + disk write)
at least for the type of simple I/O operations that I'm 
used to.

Can you tell me if its normal for netcdf to take a long
time to write across the ethernet, and if there are any
common pitfalls that people run into when trying to 
do so?  I realize that this might be dependent on 
my code, so if it would help you to see some of the 
netcdf call's that I'm using, please let me know.

Thanks in advance,

Quinn Sloan

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    • From: Mike Hamilton
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    • From: Russ Rew