so more on the relationship between systems and initd
Although the systemd process replaces the init process (quite literally, /sbin/init is now a symbolic link to /usr/lib/systemd/systemd) for starting services at boot time and changing runlevels, systemd provides much more control than the init process does while still supporting existing init scripts
gheist
It is actually second attempt on parallelized init, previous in RHEL6 (and ubuntu 12) was upstart, and it already did kickass to track startup dependencies and try to prime up startup scripts in parallel...
gheist
Red hat 7 should be 1/7th of all versions covered if we count using fingers, the inittab solution works for all versions before v7, so it is technically valid until the point asker admitted using RHEL7...
the /etc/inittab on CentOS7 explains the difference:
# inittab is no longer used when using systemd.
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
# To view current default target, run:
# systemctl get-default
# To set a default target, run:
# systemctl set-default TARGET.target
so more on the relationship between systems and initd
Although the systemd process replaces the init process (quite literally, /sbin/init is now a symbolic link to /usr/lib/systemd/systemd) for starting services at boot time and changing runlevels, systemd provides much more control than the init process does while still supporting existing init scripts