This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
>To: address@hidden >From: address@hidden >Subject: Speed of Data Axxess >Organization: Memorial Sloan Kettering Cancer Center >Keywords: 199710081902.NAA13025 Hi Dr. Erdi, > The system developed at our center Memorial Sloan Kettering > Cancer Center is using netCDF 1.3 version (dating to 1993) running on > OpenVMS 6.2. We are reading large data files (>50Mbytes) and saving > them on a network of 100 MB/sec. It takes about 50 seconds which is > too slow. > > In your later versions is there an improvement in speed for data > access? > > If I update the netCDF software to version 3 will I have speed > improvements? Yes, it will probably be faster. The new version may be much faster, depending on whether you are writing out arrays of floating-point numbers or not, and whether your OpenVMS platform uses IEEE floating-point as its native representation. If you are writing out floating-point arrays, the new version is probably much faster because it replaces one-function-call-per-float with a single call for an array of floats, which eliminates much of the function call overhead. There are additional efficiencies in optimizations possible when converting from native floating-point to IEEE format, if that conversion is necessary. It's definitely worth a try. We would be interested in hearing about the results. --Russ