Documentation Boot Beat

From FedoraProject

(Difference between revisions)
Jump to: navigation, search
(document /run change)
(Faster boot with host-only initramfs: Copy from the feature page was much better than mine, we'll use that.)
(18 intermediate revisions by 6 users not shown)
Line 1: Line 1:
 
{{header|docs}}
 
{{header|docs}}
 
{{Docs_beat_open}}
 
{{Docs_beat_open}}
{{Draft| '''NEED rewrite''': insert the '''boot options''', remove or move some contents to other places, perhaps split it}}
 
= systemd =
 
  
'''systemd''' is a system and service manager, replacement for SysVinit and Upstart. After a six months shift, during which it has been more granularly tested, Fedora 15 brings in, by default, a new system daemon whose code is designed from scratch, with the objective to take the maximum advantage offered by modern Linux kernel.  
+
= Faster boot with host-only initramfs =
 +
This Fedora release builds an initramfs tailored especially for your computer hardware, allowing faster boot. If you change your machine or significant hardware, you might have to boot with the "Rescue" boot entry and execute "dracut --regenerate-all". If you want your initramfs to be hardware independent, install the "dracut-nohostonly" rpm package. If you don't want rescue images at all (like in virtual machines), install the "dracut-norescue" rpm package.
  
With '''systemd''', Fedora 15 boots-up faster, particularly on SSD; native systemd service configuration files (or units) are much easier to understand and configure compared to sysvinit scripts, as systemd uses <code>.service</code> files instead of bash script; all daemons are sorted into their own Linux cgroups, which you may explore beneath <code>/cgroup/systemd</code> in the file system hierarchy; administrative features of the init system are considerably extended.
+
= systemd =
 
+
Refer to https://fedoraproject.org/wiki/Systemd for more complete information on systemd in Fedora.
+
 
+
= 4kB Sector disk boot support =
+
 
+
Booting 4kB sector disks in UEFI environments is now supported.
+
 
+
== /run directory ==
+
 
+
Fedora 15 has a /run directory for storing runtime data.  /run is now a tmpfs, and /var/run is bind mounted to it. /var/lock is bind mounted to /run/lock. Applications can use /run the same way as /var/run.  Several programs including udev, dracut, mdadm, mount and initscripts used used hidden directories under /dev for runtime data during early bootup before /var is mounted.  However /dev/ is supposed to be used for only device nodes and there is consensus between major distributions to shift to using /run instead.  Fedora 15 is leading this change and the change including the benefits are explained in more detail [http://lists.fedoraproject.org/pipermail/devel/2011-March/150031.html here].
+
 
+
== /var/run and /var/lock ==
+
  
/var/run and /var/lock are now bind mounted to /run and /run/lock from tmpfs, and hence emptied on reboot. Applications must ensure to recreate their own files/dirs on startup, and cannot rely that doing this at package installation will suffice. It is possible to use systemd's tmpfiles.d mechanism to recreate directories and files beneath /var/run and /var/lock on boot, if necessary. See tmpfiles.d(5) for details (http://0pointer.de/public/systemd-man/tmpfiles.d.html) and the conf files in /etc/tmpfiles.d for examples of such configuration.  Fedora packaging guidelines for tmpfiles.d is at
+
== Modular service configuration with drop-in files ==
 +
systemd will now look for configuration directives for a service as `/etc/sytemd/system/foobar.service.d/*.conf`, making site-specific changes easier to deploy and distribute .
  
http://fedoraproject.org/wiki/Packaging:Tmpfiles.d
+
== graphing the boot process ==
 +
- systemd-analyze can now use the GraphViz `dot` tool to generate graphs of the boot process. GraphViz can be installed with `yum install graphviz` and will create a representation of the full boot process with `systemd-analyze dot | dot -Tsvg > systemd.svg` More refined plots can be generated with the optional arguments "--order" "--require" "--from-pattern=" and "--to-pattern="
  
 +
For more details and examples, see `man 1 systemd-analyze`.
  
 +
== PrivateTmp ==
 +
Services with a PrivateTmp= directory defined in their configuration make use of a private temporary directory that is shared by all processes of the service. These temporary files are deleted when the service is stopped.
 
[[Category:Docs Project]]
 
[[Category:Docs Project]]
 
[[Category:Draft documentation]]
 
[[Category:Draft documentation]]
 
[[Category:Documentation beats]]
 
[[Category:Documentation beats]]

Revision as of 03:14, 15 April 2013

DocsProject Header docTeam1.png
Note.png
Beat is open
This beat is now ready to have Fedora 21 content added by the beat writer


Contents

Faster boot with host-only initramfs

This Fedora release builds an initramfs tailored especially for your computer hardware, allowing faster boot. If you change your machine or significant hardware, you might have to boot with the "Rescue" boot entry and execute "dracut --regenerate-all". If you want your initramfs to be hardware independent, install the "dracut-nohostonly" rpm package. If you don't want rescue images at all (like in virtual machines), install the "dracut-norescue" rpm package.

systemd

Modular service configuration with drop-in files

systemd will now look for configuration directives for a service as `/etc/sytemd/system/foobar.service.d/*.conf`, making site-specific changes easier to deploy and distribute .

graphing the boot process

- systemd-analyze can now use the GraphViz `dot` tool to generate graphs of the boot process. GraphViz can be installed with `yum install graphviz` and will create a representation of the full boot process with `systemd-analyze dot | dot -Tsvg > systemd.svg` More refined plots can be generated with the optional arguments "--order" "--require" "--from-pattern=" and "--to-pattern="

For more details and examples, see `man 1 systemd-analyze`.

PrivateTmp

Services with a PrivateTmp= directory defined in their configuration make use of a private temporary directory that is shared by all processes of the service. These temporary files are deleted when the service is stopped.