Previous versions of Fedora Linux used the (very) old, tried and true SysV Init script startup. Starting with Fedora 15 and continuing with Fedora 16, the migration from SysV Init to systemd has nearly completed.
Fedora experimented for a bit with a startup tool called Upstart, but that was dropped as it was not enough of a change to warrant continuing. SystemV Init, which has been around since about 1969, has not changed significantly in over 40 years. It had to start services serially and this slowed down the startup sequence.
The systemd daemon improves on startup by starting processes that need to be started in parallel as much as possible. It also only starts processes that need to be started.
Note that systemd is backwards compatible with SystemV Init scripts. That means that it won’t break services that have not converted to systemd, such as vendor products designed to be started on boot.
This section covers Linux startup using systemd—sort of. There is already a lot of really good information out there about systemd. Most of it is better than I could write here. So I have provided below a list of links to the best information sources.
Here is a list of links to more detailed information about systemd startup.
- There is a good practical guide at the Fedora Project. This site has pretty much everything you need to know in order to configure, manage and maintain a Fedora computer using systemd.
- For detailed technical information about systemd and the reasons for creating it, check out this Description of systemd at Freedesktop.org.
- A basic introduction to systemd at Linux.com.
- Managing services on systemd at Linux.com.
- And more advanced systemd information and tips at Linux.com.
Here are a series of articles written by Lennart Poettering, the designer and primary developer behind systemd. These are deeply technical articles that are clearly for Linux System Administrators.
- Rethinking PID 1
- systemd for Administrators, Part 1
- systemd for Administrators, Part II
- systemd for Administrators, Part III
- systemd for Administrators, Part IV
- systemd for Administrators, Part V
- systemd for Administrators, Part VI
- systemd for Administrators, Part VII
- systemd for Administrators, Part VIII
- systemd for Administrators, Part IX
- systemd for Administrators, Part X
- systemd for Administrators, Part XI