Load and save the system random seed at boot and shutdown
systemd-random-seed.service
/lib/systemd/systemd-random-seed
systemd-random-seed.service is a service that restores the random seed of the system at early-boot and saves it at shutdown. See random(4) for details. Saving/restoring the random seed across boots increases the amount of available entropy early at boot. On disk the random seed is stored in /var/lib/systemd/random-seed.