It appears that on 32bit systems you cannot allocate and correctly use more than 3GB of RAM for each ndb data node even if you have a PAE kernel.

The current 6.3.17 mysql cluster 32bit release doesn't correctly report memory allocation errors and produces random segmentation faults which leave you clueless. If you're running under these conditions than you'll almost sure get past the problems by using a 64bit release on a 64bit OS.