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What Arch Linux's switch to systemd means for users
===================================================
:copyright 2012 Luke Shumaker
This is based on a post on [reddit][1], published on 2012-09-11.
[1]: http://www.reddit.com/r/archlinux/comments/zoffo/systemd_we_will_keep_making_it_the_distro_we_like/c66nrcb
systemd is a replacement for UNIX System V-style init; instead of
having `/etc/init.d/*` or `/etc/rc.d/*` scripts, systemd runs in the
background to manage them.
This has the **advantages** that there is proper dependency tracking,
easing the life of the administrator and allowing for things to be run
in parallel safely. It also uses "targets" instead of "init levels",
which just makes more sense. It also means that a target can be
started or stopped on the fly, such as mounting or unmounting a drive,
which has in the past only been done at boot up and shut down.
The **downside** is that it is (allegedly) big, bloated[[1](#foot1)], and does
(arguably) more than it should. Why is there a dedicated systemd-fsck?
Why does systemd encapsulate the functionality of syslog? That, and it
means somebody is standing on my lawn.
The **changes** an Arch user needs to worry about is that everything
is being moved out of `/etc/rc.conf`. Arch users will still have the
choice between systemd and SysV-init, but rc.conf is becoming the
SysV-init configuration file, rather than the general system
configuration file. If you will still be using SysV-init, basically
the only thing in rc.conf will be `DAEMONS`.[[2](#foot2)] For now
there is compatibility for the variables that used to be there, but
that is going away.
[<span id="foot1">1</span>]
*I* don't think it's bloated, but that is the criticism. Basically, I
discount any argument that uses "bloated" without backing it up. I
was trying to say that it takes a lot of heat for being bloated, and
that there is be some truth to that (the systemd-fsck and syslog
comments), but that these claims are largely unsubstantiated, and more
along the lines of "I would have done it differently". Maybe your
ideas are better, but you haven't written the code.
I personally don't have an opinion either way about SysV-init vs
systemd. I recently migrated my boxes to systemd, but that was because
the SysV init scripts for NFSv4 in Arch are problematic. I suppose
this is another **advantage** I missed: *people generally consider
systemd "units" to be more robust and easier to write than SysV
"scripts".*
I'm actually not a fan of either. If I had more time on my hands, I'd
be running a `make`-based init system based on a research project IBM
did a while ago. So I consider myself fairly objective.
[<span id="foot2">2</span>] You can still have `USEDMRAID`, `USELVM`, `interface`, `address`,
`netmask`, and `gateway`. But those are minor.
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