forked from lix-project/lix
* Section about garbage collection.
This commit is contained in:
parent
cbe8de592d
commit
ee5dcfade2
|
@ -110,6 +110,10 @@ more-or-less cracked. We don't currently depend very much on the
|
|||
collision-resistance of MD5, but we will once we start sharing build
|
||||
results between users.</para></listitem>
|
||||
|
||||
<listitem><para>It would be useful to have an option in
|
||||
<command>nix-env --delete-generations</command> to remove non-current
|
||||
generations older than a certain age.</para></listitem>
|
||||
|
||||
</itemizedlist>
|
||||
|
||||
</appendix>
|
||||
|
|
|
@ -41,11 +41,11 @@ during an upgrade in which part of the old version and part of the new
|
|||
version are simultaneously visible (which might well cause the
|
||||
component to fail).</para></listitem>
|
||||
|
||||
<listitem><para>Likewise, it is possible to atomically roll-back after
|
||||
<listitem><para>Likewise, it is possible to atomically roll back after
|
||||
an install, upgrade, or uninstall action. That is, in a fast (O(1))
|
||||
operation the previous configuration of the system will be
|
||||
restored. This is because upgrade or uninstall actions doesn't
|
||||
actually remove components from the system.</para></listitem>
|
||||
operation the previous configuration of the system will be restored.
|
||||
This is because upgrade or uninstall actions doesn't actually remove
|
||||
components from the system.</para></listitem>
|
||||
|
||||
<listitem><para>Unused components can be
|
||||
<emphasis>garbage-collected</emphasis> automatically and safely.
|
||||
|
@ -111,7 +111,7 @@ deployment of a complete web server with all its configuration files,
|
|||
static pages, software dependencies, and so on. Nix's advantages for
|
||||
software deployment also apply here, for instance, the ability
|
||||
trivially to have multiple configurations at the same time, or the
|
||||
ability to do roll-backs.</para></listitem>
|
||||
ability to do rollbacks.</para></listitem>
|
||||
|
||||
</itemizedlist>
|
||||
|
||||
|
|
|
@ -332,8 +332,70 @@ This will <emphasis>not</emphasis> change the
|
|||
|
||||
<sect1 id='sec-garbage-collection'><title>Garbage collection</title>
|
||||
|
||||
<para><command>nix-env</command> operations such as upgrades
|
||||
(<option>-u</option>) and uninstall (<option>-e</option>) never
|
||||
actually delete components from the system. All they do (as shown
|
||||
above) is to make a new user environment that no longer contains
|
||||
symlinks to the <quote>deleted</quote> components.</para>
|
||||
|
||||
<para>Of course, since disk space is not infinite, unused components
|
||||
should be removed at some point. You can do this by running the Nix
|
||||
garbage collector. It will remove from the Nix store any component
|
||||
not used (directly or indirectly) by any generation of any
|
||||
profile.</para>
|
||||
|
||||
<para>Note however that as long as old generations reference a
|
||||
component, it will not be deleted. After all, we wouldn't be able to
|
||||
do a rollback otherwise. So in order for garbage collection to be
|
||||
effective, you should also delete (some) old generations. Of course,
|
||||
this should only be done if you are certain that you will not need to
|
||||
roll back.</para>
|
||||
|
||||
<para>To delete all old (non-current) generations of your current
|
||||
profile:
|
||||
|
||||
<screen>
|
||||
$ nix-env --delete-generations old</screen>
|
||||
|
||||
Instead of <literal>old</literal> you can also specify a list of
|
||||
generations, e.g.,
|
||||
|
||||
<screen>
|
||||
$ nix-env --delete-generations 10 11 14</screen>
|
||||
|
||||
</para>
|
||||
|
||||
<para>After removing appropriate old generations you can run the
|
||||
garbage collector as follows:
|
||||
|
||||
<screen>
|
||||
$ nix-collect-garbage</screen>
|
||||
|
||||
You can alo first view what files would be deleted:
|
||||
|
||||
<screen>
|
||||
$ nix-collect-garbage --print-dead</screen>
|
||||
|
||||
Likewise, the option <option>--print-live</option> will show the paths
|
||||
that <emphasis>won't</emphasis> be deleted.</para>
|
||||
|
||||
<sect2><title>Garbage collector roots</title>
|
||||
|
||||
<para>TODO</para>
|
||||
|
||||
<para>The garbage collector uses as roots all store expressions
|
||||
mentioned in all files with extension <filename>.gcroot</filename> in
|
||||
the directory
|
||||
<filename><replaceable>prefix</replaceable>/var/nix/gcroots/</filename>,
|
||||
or in any file or directory symlinked to from that directory. E.g.,
|
||||
by default,
|
||||
<filename><replaceable>prefix</replaceable>/var/nix/gcroots/</filename>
|
||||
contains a symlink to
|
||||
<filename><replaceable>prefix</replaceable>/var/nix/profiles/</filename>,
|
||||
so all generations of all profiles are also roots of the collector.</para>
|
||||
|
||||
</sect2>
|
||||
|
||||
</sect1>
|
||||
|
||||
|
||||
|
|
Loading…
Reference in a new issue