Hello everyone, I have created rather large 3-D binary arrays in IDL that I save as unformatted data using writeu. When the number of elements contained in the volume gets to be around 2,300,000,000 if I attempt to writeu or readu the volume, I am kicked out of IDL with a segmentation fault. I don't think it's a memory issue, I'm running 64-bit IDL on a 64-bit linux running redhat enterprise with 12 GB of ram, and I can save arrays that have larger file sizes as long as they have a smaller amount of actual elements. One workaround I've used for 'writeu' is to write to the file in chunks, by using a for loop to write each slice of the volume individually. This works for saving the volume, but then I have no way to re-open the volume in IDL without the readu segmentation fault! Anyone have any ideas for what could be causing this? I'm running IDL Version 6.2. Overall, it seems there is a 32-bit limitation on the number of elements written by writeu and opened by readu even on a 64bit system. Any ideas of how I can work around this using readu? Thanks for any insight you can give!