Filling SMR disks with random data efficiently

For SMR (shingled magnetic recording) disks, random writing is laughably inefficient. But if you have one SMR disk anyway (e.g., it came with a new computer) and want to deploy FDE (full disk encryption) on it, you can try to increase the block size to make the writing process more sequential (less random). For example:

# dd bs=128M if=/dev/urandom of=/dev/sdX

I wiped out a 2-TB 2.5-inch SMR disk (WD20SPZX) this way within 7 or 8 hours. Default parameters roughly take twice long.

Until recently, the disk wiping utility (when configuring encrypted volumes) in Debian Installer still hasn't optimized for SMR, so you need to wipe the disk before configuring FDE.