(Should work in CentOS / RHEL or any system using dracut too)
http://reboot.pro/topic/14547-linux-load-your-root-partition-to-ram-and-boot-it/
https://forums.centos.org/viewtopic.php?t=46678
- Fedora 33 on external HDD with /home and /boot/efi as separate mountpoints and formatted in BTRFS.
- Kernel 5.9.14-200.fc33.x86_64
- 24 GB RAM