I just use fallocate to create a 1GB or 2GB file, depending on the total storage size. It has saved me twice now. I had a nasty issue with a docker container log quickly filling up the 1GB space before I could even identify the problem, causing the shell to break down and commands to fail. After that, I started creating a 2GB file.
Interesting! I did `fallocate -l 1G myfile` - very fast. Its all zeros but probably won't be compressed by the filesystem since its created with the fallocate() system call.