> > On Apr 5, 2011, at 5:01 PM, Unidata IDV Support wrote: > > >> First, let me stipulate that I know IDV does many things Panoply doesn't, > >> and I use and proselytize it regularly. But lately i have run into a > >> couple discrepancies where Panoply can handle data through OPeNDAP that > >> IDV struggles with due to performance reasons. I wonder if there is > >> anything you can do to catch up... > >> > >> Case #1: MODIS Level 3 data in OPeNDAP, hyrax variety (please do not > >> advertise this URL, though, it is intended primarily for machine use by > >> our Giovanni app): > >> > >> http://disc1.gsfc.nasa.gov/opendap/Aqua_MODIS_Level3/MYD08_D3.051/2011/MYD08_D3.A2011001.051.2011005093254.pscs_000500527176.hdf > >> > >> This is a very large file with many, many variables. That said, Panoply > >> takes about 20-25 seconds to inventory the variables in the file, and > >> another 5-10 secs to display one. IDV takes ~6 minutes to inventory the > >> data file on a MacBook Pro, but then about the same time as Panoply to > >> display one variable. (BTW, this is actually a subset of the original > >> MODIS L3 file, which is even larger!) > >> > > > > > > I tried this url and it took about 15 seconds, so it really depends on the > > network traffic and loads of the server. > > And yet, every time I have tried this URL on my laptop, it has taken at least > 5 minutes to inventory the file. The server has > 90% idle (load average > about 2) during the transaction and usually serves very little data either to > the public or our internal machines, due to its less-popular holdings. And > this does not explain why Panoply, when executed either shortly before or > shortly after, takes less than 30 seconds to inventory the same URL. > > > > > > >> Case #2 Merged IR in OPeNDAP of the GrADS Data Server (GDS) variety: > >> http://disc2.nascom.nasa.gov:80/dods/MergedIR > >> > >> GDS presents the whole dataset as one huge "file". Panoply can display > >> this after a few minutes of churning; however IDV eventually errors out > >> after several minutes with a message about Java heap space. > >> > >> Case #2 would be more useful for us to get fixed--we had a user asking us > >> how to read the Merged IR through IDV. > >> > >> Anything you can do? > > > > My IDV has 4G memory, and it has no problem to load the data. So the > > solution for your user is to increase the memory. > > What do you mean your "IDV has 4G memory"? Is there some way of allocating > more memory to that particular app on a Mac laptop? (I know there was on old > Mac operating systems, but I cannot find the mechanism on Snow Leopard.) Or > do you mean I have to add more physical memory to my laptop? It actually > currently has 4 GB. Also, since many of our users come from the developing > world, or small institutions, we cannot always suggest to them to upgrade > their hardware. Yes, you can allocate more memory to the IDV, see the FAQ here: http://www.unidata.ucar.edu/software/IDV/docs/userguide/Faq.html. And you still need to subset the time dimension of the dataset when creating the display. The idea of input the url like this http://disc2.nascom.nasa.gov/dods/MergedIR.ch4[0:5][0:0][0:3297][0:9895]lon[0:9895]lat[0:3297]lev[0:0].dds is bad, you can subset after loading the dataset http://disc2.nascom.nasa.gov/dods/MergedIR, and then create the display. Yuan > > > > > > > > > Yuan > >> -- > >> Dr. Christopher Lynnes NASA/GSFC, Code 610.2 phone: 301-614-5185 > >> > >> > >> > > > > > > Ticket Details > > =================== > > Ticket ID: FDK-698636 > > Department: Support IDV > > Priority: Normal > > Status: Open > > > > -- > Dr. Christopher Lynnes NASA/GSFC, Code 610.2 phone: 301-614-5185 > > > Ticket Details =================== Ticket ID: FDK-698636 Department: Support IDV Priority: Normal Status: Open
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