And one last point.  In the blog comments, I wrote this, which I think sums up my view of the performance discussion:<p>...it&#x27;s worth noting that many of the tricky things about tuning hdf5 performance are not unique to HDF5. For storing ND data, there will always be decisions to make about when to load data into RAM vs. accessing it on demand, whether or not to store the data in &quot;chunks&quot;, what the size of those chunks should be (based on your anticipated access patterns), whether&#x2F;how to compress the data, etc. These are generally hard problems; we can&#x27;t blame HDF5 for all of them.