initrdn

Initrdn is a term used in some Linux boot discussions to describe a method in which the initial root filesystem is retrieved over a network during early boot, rather than being loaded from local storage. The term is not part of a formal standard and does not reflect an official kernel feature in mainstream distributions.

It builds on the long-standing concept of an initial ramdisk (initrd) or initial RAM filesystem (initramfs) by removing the requirement for a locally stored root image and allowing diskless or stateless operation.

Operation: The kernel boots a minimal bootstrapping environment capable of network access, contact a remote server, download or mount a remote image, and switch to the network-provided root filesystem. A typical design may employ a small in-kernel bootstrap or a privileged early userspace, plus a remote transport protocol (for example TFTP, NBD, iSCSI, or HTTP) to fetch the image.

Use cases: diskless workstations, lab automation, test farms, or environments where nodes must boot from centralized storage.

Limitations and status: Security, reliability, and network dependency are key concerns. Because the root filesystem depends on a network, boot failure or network issues can prevent startup. There is no standardized implementation in mainline Linux; patches and experimental implementations appear in research or hobbyist projects.

Related topics include initrd, initramfs, network boot, and PXE.