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Re: [ferret_users] Compressed ferret output incompatibe with netcdf java apps

Hi Russ,
We reported this to Unidata and they found that this was an issue with the netCDF java library. They've made a fix which will be in the upcoming netCDF-java library version 4.6.5.


On 1/28/2016 10:52 PM, Russ Fiedler wrote:


This is possibly a problem with netcdf java rather than ferret but anyway...

If we make a variable and save it in compressed netcdf4 format it appears that java based netcdf software han't handle it.


yes? let v=i[i=1:20]+j[j=1:20]
yes? save/file=cmp.nc/ncformat=netcdf4/def v ! compressed (actually it's larger but just an example)
yes? save/file=uncmp.nc/ncformat=netcdf4 v      ! uncompressed

Now loading up in Panopoly (and another of our in house apps which is where we spotted the problem).When we try to operate on v we get a message about an an unknown filter type being zero for the compressed version

java.lang.RuntimeException: Unknown filter type=0
at ucar.nc2.iosp.hdf5.H5tiledLayoutBB$DataChunk.getByteBuffer(H5tiledLayoutBB.java:198)

The uncompressed version is fine since there are no filters being applied.

Now, here's where it gets weird. If nccopy is used to convert the two files to compressed netcdf4 style the originally compressed file is still giving Panopoly grief but the newly compress file is handled just fine!

xwing-hf% nccopy -k 3 -d 1 cmp.nc cmp_ncopy.nc          ! Still no good
xwing-hf% nccopy -k 3 -d 1 uncmp.nc uncmp_ncopy.nc ! compressed file is fine!!!

Any clues? A known issue?

Occurs for V6.95, V6.96 and earlier by the looks.


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