Dracut (software)


Dracut is a set of tools that provide enhanced functionality for automating the Linux boot process. The tool named dracut is used to create a Linux boot image by copying tools and files from an installed system and combining it with the Dracut framework, which is usually found in /usr/lib/dracut/modules.d.
Unlike existing Linux boot images, the Dracut framework attempts to introduce as little hard-coded logic into the initramfs as possible. The initramfs has essentially one purpose: locating and mounting the real root file system so that the boot process can transition to it. This functionality is dependent on device availability. Therefore, instead of having hard-coded scripts to determine device availability and suitability, Dracut's initramfs depends on the Linux device manager to create symbolic links to device nodes. When the root file system's device node appears, Dracut mounts it as the new root file system. This helps to keep the time required in initramfs down so that things like a 5-second boot are now made possible.
Most of the initramfs generation functionality in Dracut is provided by generator modules that are sourced by the main dracut tool to install specific functionality into the initramfs. They live in the modules subdirectory, and use functionality provided by dracut-functions to do their work.
Currently, dracut supports booting from btrfs, DM RAID, MD RAID, LVM2, device mapper multipath I/O, dm-crypt, cifs, FCoE, iSCSI, NBD and NFS.

Adoption

Redhat is the original author of dracut.
Redhat-derived distributions use dracut for initramfs creation.
Use outside Redhat-derived distributions is limited.
Distributions which include dracut, but do not use by default for initramfs creation: