In a quirky experiment, the author created an ext4 file system with a billion empty files. They simplified the process by writing a Rust program, which made the task more manageable compared to previous attempts using clunky scripts. The disk image started as a terabyte-size sparse file, taking up no space until the file system was added. This resulted in an image using 276 GiB of disk space. It took about 26 hours to create on the author’s desktop machine. The author did not measure compression times, but the sizes of the compressed images are provided for reference. The purpose of such a file system could be for benchmarking operations on large directories.
https://blog.liw.fi/posts/2024/billion/