Hello Donald, To answer your final question first, yes, this is potentially expected behavior; the underlying file I/O is handled by libhdf5, and the files being written are larger than those written natively by netCDF3. There are several things that can cause netCDF4 files to be much larger when converted from netCDF3. Fill values and chunks sizes are the first things that come to mind; depending on the default chunk size and the amount of data in the file, the size of the final file may be inflated when the fill value is written out to populate any under-filled chunk. As you've discovered, unlimited dimensions can also be a source of unexpected increase in file size. If you can provide a sample file I'd be happy to look and see if there's a way that it can be made smaller using nccopy; otherwise, ncks may be a better option. I'm not certain what ncks is doing, but I will take a look to see if it is doing something that can be integrated into nccopy. Thanks! -Ward > If I use nccopy (nccopy -k netCDF-4 or nccopy -4 or nccopy -7) to convert > a file from version 3 to version 4, that file increases in size by a factor > of 5 in one case and a factor of 20 in another. If I use ncks -7, the file > size is within 6% of the original. If I run nccopy with the -u flag to > remove unlimited dimensions, it is also within a few percent. > > Can you explain this? Is this expected behavior? > > -- > Donald Stark > NCAR RAL JNT/DTC > Address: FL3-1042 > Phone: 303.497.2472 > Email: address@hidden > Web: www.rap.ucar.edu/~stark > > Ticket Details =================== Ticket ID: VEG-361627 Department: Support netCDF Priority: Normal Status: Closed =================== NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.