@mcc @rotopenguin @Foritus I don’t think I’ve ever seen a Mac OS sparse bundle shrink.A ZFS bitstream file works roughly that way, though it’s not carved up into smaller, FAT32-friendly chunks. You get one using ‘zfs send’, and you should be able to mount it directly. I don’t personally use btrfs, but I would expect it to have similar capabilities.Shrinking such a file when data is removed would involve another ‘zfs send’ operation to a new file on the disk, so you would need at least the size of the file in free space.