Patrick, This turns out to be a known problem with HDF5 performance: http://mail.lists.hdfgroup.org/pipermail/hdf-forum_lists.hdfgroup.org/2012-November/006195.html --Russ > In this case, no b-trees are involved, because the data storage is > contiguous, not chunked (according to ncdump -h -s). So I'm > surprised how slow the strided netCDF access is, and suspect there > might be a performance bug in how netCDF-4 uses the HDF5 API for > strided access. > > --Russ > > Russ Rew UCAR Unidata Program > address@hidden http://www.unidata.ucar.edu > > Russ Rew UCAR Unidata Program address@hidden http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: ZFB-587742 Department: Support netCDF Priority: Normal Status: Closed