This flow chart illustrates the ordering of the services, if systemd is used in the dracut initramfs.
systemd-journal.socket | v dracut-cmdline.service | v dracut-pre-udev.service | v systemd-udevd.service | v local-fs-pre.target dracut-pre-trigger.service | | v v (various mounts) (various swap systemd-udev-trigger.service | devices...) | (various low-level (various low-level | | | services: seed, API VFS mounts: v v v tmpfiles, random mqueue, configfs, local-fs.target swap.target dracut-initqueue.service sysctl, ...) debugfs, ...) | | | | | \_______________|____________________ | ___________________|____________________/ \|/ v sysinit.target | _________________/|\___________________ / | \ | | | v | v (various | rescue.service sockets...) | | | | v v | rescue.target sockets.target | | | \_________________ | emergency.service \| | v v basic.target emergency.target | ______________________/| / | | v | dracut-pre-mount.service | | | v | sysroot.mount | | | v | initrd-root-fs.target (custom initrd services) | | v | dracut-mount.service | | | v | initrd-parse-etc.service | | | v | (sysroot-usr.mount and | various mounts marked | with fstab option | x-initrd.mount) | | | v | initrd-fs.target \______________________ | \| v initrd.target | v dracut-pre-pivot.service | v initrd-cleanup.service isolates to initrd-switch-root.target | v ______________________/| / | | initrd-udevadm-cleanup-db.service | | (custom initrd services) | | | \______________________ | \| v initrd-switch-root.target | v initrd-switch-root.service | v switch-root