19.7 How to Use Per-Variable Compression in NetCDF-4
Some advice about using compression.
- The zlib library accepts a deflate factor of 0 through 9.
- We do not always see much difference in compression by using higher
numbers for the deflate factor, but there is certainly a performance
- Therefore we suggest trying deflate level of 1 or 2. You may have
- Compression cannot be used when writing data with parallel
I/O. (It can be used when reading data with parallel I/O.)
- The HDF5 library also offers szlib compression, based on the szlib
compression library. Since this library has some license
restrictions (for commercial users creating datasets), we don't
support creating szlib compressed data.
- The nccopy utility can apply a uniform level of compression to
all the variables in a file. Use nccopy to experiment with whether
compression is worthwhile, and what level is optimal.