Blosc compression of HDF5 files in Julia is implemented at https://github.com/timholy/HDF5.jl/issues/174 <https://github.com/timholy/HDF5.jl/issues/173>
Cursory testing seems to indicate that it is within a factor of 2 of uncompressed HDF5 (as opposed to the orders-of-magnitude penalty of zlib), and achieves pretty good compression (actually better than zlib), although I've only tried it out on trivial data. It would be great to have people bang on it some more with real data.
