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diff --git a/doc/manual/troubleshooting.xml b/doc/manual/troubleshooting.xml index 3787ddcd93f5..fb6e1bd63c9c 100644 --- a/doc/manual/troubleshooting.xml +++ b/doc/manual/troubleshooting.xml @@ -72,4 +72,44 @@ other.</para> </sect1> +<sect1><title><quote>Too many links</quote> error in the Nix +store</title> + + +<para>Symptom: when building something, you get an error message such as + +<screen> +... +<literal>mkdir: cannot create directory `/nix/store/<replaceable>name</replaceable>': Too many links</literal></screen> + +</para> + +<para>This is usually because you have more than 32,000 subdirectories +in <filename>/nix/store</filename>, as can be seen using <command>ls +-l</command>: + +<screen> +$ ls -l /nix/store +drwxrwxrwt 32000 nix nix 4620288 Sep 8 15:08 store</screen> + +The <literal>ext2</literal> file system is limited to a inode link +count of 32,000 (each subdirectory increasing the count by one). +Furthermore, the <literal>st_nlink</literal> field of the +<function>stat</function> system call is a 16-bit value.</para> + +<para>This only happens on very large Nix installations (such as build +machines).</para> + +<para>Quick solution: run the garbage collector.</para> + +<para>Real solution: put the Nix store on a file system that supports +more than 32,000 subdirectories per directory, such as ReiserFS. +(This doesn’t solve the <literal>st_nlink</literal> limit, but +ReiserFS lies to the kernel by reporting a link count of 1 if it +exceeds the limit.)</para> + +</sect1> + + + </appendix> |