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Problem with ".cdf" files on Windows


I just ran into a strange and troubling problem using netCDF on from IDL on
Windows (NT 4.0).  I created a large, 430MB netCDF file called "test.cdf".
As soon as I point Windows Explorer to the directory containing that file I
observe "explorer.exe" consuming 100% of the CPU and up to 900MB of RAM (on
a workstation with 1GB of RAM).  The workstation is essentially locked up.
It is not possible to delete or rename the file for many minutes, even from
another workstation, because Windows claims there has been a "sharing

Here is what I believe is happening:  Windows thinks that files with a
".cdf" extension are "Channel files", which are used to display Web
channels.  As soon as Explorer opens a directory containing a ".cdf" file it
scans that file, even without the file itself being selected.  If the file
is huge it consumes the entire resources of the workstation for many

If I create a file called "test.ncd" rather than "test.cdf" things work
fine.  If I use Explorer to rename "test.ncd" to "test.cdf" the problem
immediately recurs.

Moral of the story:  don't use the extension ".cdf" for netCDF files on

Is this a commonly known problem?  Is there a FAQ for netCDF where this is


Mark Rivers
Building 434A
Argonne National Laboratory
Argonne, IL 60439
Phone:  630-252-0422
FAX:    630-252-0443
e-mail: rivers@cars.uchicago.edu