Strangely enough I'm doing the exact same thing. My case seems a bit more complicated since we're dumping not only long arrays of floats, but also a bunch of miscellaneous data (datetimes, unique datapoints, ids) right before/after those numbers. So it's even more of a nightmare... Some of these files have version numbers in the 30's (oh yeah, and file versions are based on file size.)

And did I mention that the file handles are kept open for the whole program duration (might be multiple hours) ? That's fun, data loss is almost a daily occurrence. It's the main thing I'm refactoring right now.