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Re: THREDDS and grib

these are all good questions - there have been similar reports of the agg cache
not working like it
should. i will have to reproduce to see whats happening.

Kevin O'Brien wrote:


Hi John -

I tried what you suggested and it didn't seem to have a significant
effect in making the initial access of the aggregated dataset quicker.
It still took over a minute and a half to open the dataset.  I've pasted
the xml config that I used to define the new aggregation below.  To be
honest, I'm actually kind of glad because I wasn't looking forward to
modifying the guts of the application which generates the xml config
automatically.... :-)

I guess I can understand and probably even accept the fact that for the
first time the dataset is accessed, things will be a little slow.  After
that, I presume the dataset is available in the cache, and of course
subsequent accesses prove that it is because the response is quite
quick.    However, if the tomcat server is restarted, it seems like
whatever is in the cache is ignored and the cache entries have to be
rebuilt.   I have my aggregation cache set like so:

 <AggregationCache>



<dir>/home/pmel/DataPortal/apache-tomcat-5.5.25/content/thredds/cacheAged/</dir>


   <scour>24 hours</scour>
   <maxAge>90 days</maxAge>
 </AggregationCache>

Does that seem correct? Also, as an aside, you mention that you thought
this would be quicker because it avoids the OPeNDAP URL's....Shouldn't
there be some client side caching done w/ the OPeNDAP datasets?  For
example, if I access a remote dataset with ncdump (or Ferret), and my
OPeNDAP caching is turned on my ~/.dodsrc file, it will cache the
response in the ~/.dods_cache directory.  Does any of that happen when
OPeNDAP URL's are accessed through TDS???

Anyway - here's the xml config I used as per your suggestion:

   <dataset ID="CM2.1U-D4_1PctTo2X_I1 atmos daily all vars
00010101-02201231_2" name="CM2.1U-D4_1PctTo2X_I1 atmos daily all vars
00010101-02201231_2"
urlPath="ipcc_ar4_CM2.1_R1_1to2x-1_daily_atmos_00010101-02201231_2">
       <serviceName>thisDODS3</serviceName>
       <netcdf
xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
         <aggregation type="union">
            <netcdf
xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
              <aggregation dimName="time" type="joinExisting">
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/pr_A2.00010101-01001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/pr_A2.01010101-02001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/pr_A2.02010101-02201231.nc"

ncoords="7300" />
              </aggregation>
            </netcdf>
            <netcdf
xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
              <aggregation dimName="time" type="joinExisting">
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmax_A2.00010101-01001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmax_A2.01010101-02001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmax_A2.02010101-02201231.nc"

ncoords="7300" />
              </aggregation>
            </netcdf>
            <netcdf
xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
              <aggregation dimName="time" type="joinExisting">
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmin_A2.00010101-01001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmin_A2.01010101-02001231.nc"

ncoords="36500" />
               <netcdf


location="file:/data/gfdl_cm2_1/CM2.1U-D4_1PctTo2X_I1/pp/atmos/ts/daily/tasmin_A2.02010101-02201231.nc"

ncoords="7300" />
              </aggregation>
            </netcdf>
         </aggregation>
       </netcdf>
   </dataset>


I'm open to any suggestions or ideas!

thanks -
kevin


John Caron wrote:

Hi Kevin:

I havent had time to reproduce this yet, but im guessing one source of
the slowdown is using opendap URLS in the compound aggregation. It
would be interesting to time 1) the single aggregations, 2) the
compound agg as it exists, and 3) the compound agg, but replace the
opendap URLs with direct netcdf files,

see attached file