Thanks, but it wasn't so much asking about storing more than you have at once, but as file systems are used, old unused space might still be occupying space in the Shufflecake scheme. Say you have that 1GB volume with three equally-sized volumes; sure, you can write ~333MB to each of them, and then delete all the files. Now according to each of the file systems, you have 0B used and 1GB free. When you try making new files after this point, will it still generate I/O errors?