Jerry,
You might also check into using NetCDF4 files with deflation instead
of .nc.gz. Your users can still download as opendap or any of the
other services. If they want netcdf4 files they can use the NetCDF
subset service or use tools like NCO that can read opendap and
generate NetCDF 3 files. You can convert NetCDF3 to NetCDF4 using
level 1 deflation using NCO ( ncks -4 -L 1 netcdf3.nc netcdf4.nc).
They should be about the same size as the nc.gz files, and will be
much faster to read since you don't have to uncompress the whole file.
-Rich
On Mon, May 2, 2011 at 2:27 PM, jerry y pan <jerry.ypan@xxxxxxxxx> wrote:
> Hi John,
> Our TDS (4.2) uses some compressed netcdf files (*.nc.gz) and it works fine,
> except that the very first access to them were slow (relatively large files,
> about 400 MB each). The subsequent accesses would be much faster, but it
> would become slow again after a while of non-activity. I can see that TDS
> uncompress these files to the temp data location, my question is that if TDS
> cleans up these temp files, which leads to the work to decompress them next
> time and hence the subsequent slowness? If so, is there a way to keep the
> cache there permanently? Or, perhaps the faster response right after the
> first access is due to in memory cache? Any configuration I could twist the
> cache?
>
>
> Thanks,
> -Jerry Pan
>
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Dr. Richard P. Signell (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598
