* Allow the size of the GC reserved file to be specified in nix.conf

  through the new `gc-reserved-space' option.

1 files changed, 20 insertions, 0 deletions

diff --git a/doc/manual/conf-file.xml b/doc/manual/conf-file.xml
index 629dd3bac788..9ff34324f20f 100644
--- a/doc/manual/conf-file.xml
+++ b/doc/manual/conf-file.xml
@@ -52,6 +52,26 @@ env-keep-derivations = false
 
   </varlistentry>
 
+  <varlistentry id="conf-gc-reserved-space"><term><literal>gc-reserved-space</literal></term>
+
+    <listitem><para>This option specifies how much space should be
+    reserved in normal use so that the garbage collector can run
+    succesfully.  Since the garbage collector must perform Berkeley DB
+    transactions, it needs some disk space for itself.  However, when
+    the disk is full, this space is not available, so the collector
+    would not be able to run precisely when it is most needed.</para>
+
+    <para>For this reason, when Nix is run, it allocates a file
+    <filename>/nix/var/nix/db/reserved</filename> of the size
+    specified by this option.  When the garbage collector is run, this
+    file is deleted before the Berkeley DB environment is opened.
+    This should give it enough room to proceed.</para>
+
+    <para>The default is <literal>1048576</literal> (1
+    MiB).</para></listitem>
+
+  </varlistentry>
+
   <varlistentry><term><literal>env-keep-derivations</literal></term>
 
     <listitem><para>If <literal>false</literal> (default), derivations