[Nexus-developers] NXmakedata with unlimited size - chunking question

[Zikovsky, Janik L.]

Hello all,

I have been calling NXmakedata() with the first dimension set to NX_UNLIMITED so as to allow extendible arrays; this is when writing to HDF5 files. This works, but from what I can tell by using hdfview, the data sets created use a chunk size of 1 in the first dimension.

This small chunk size increases writing time by approximately one thousand (!) times in my application. Does anyone know how to set the chunk size when calling NXmakedata()?

Thanks!

Janik Zikovsky
Scientific Data Analysis Group, Spallation Neutron Source