Dracut is an event-driven initramfs infrastructure. dracut (the tool) is used to create an initramfs image by copying tools and files from an installed system and combining it with the dracut framework, usually found in /usr/lib/dracut/modules.d.
By default Dracut builds big initrd because … to build smaller initrd, add to your dracut config:
# build initrd only to boot current hardware hostonly="yes"