pyrox.dev
1<section xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xmlns:xi="http://www.w3.org/2001/XInclude"
4 version="5.0"
5 xml:id="sec-nix-store-corruption">
6
7<title>Nix Store Corruption</title>
8
9<para>After a system crash, it’s possible for files in the Nix store
10to become corrupted. (For instance, the Ext4 file system has the
11tendency to replace un-synced files with zero bytes.) NixOS tries
12hard to prevent this from happening: it performs a
13<command>sync</command> before switching to a new configuration, and
14Nix’s database is fully transactional. If corruption still occurs,
15you may be able to fix it automatically.</para>
16
17<para>If the corruption is in a path in the closure of the NixOS
18system configuration, you can fix it by doing
19
20<screen>
21# nixos-rebuild switch --repair
22</screen>
23
24This will cause Nix to check every path in the closure, and if its
25cryptographic hash differs from the hash recorded in Nix’s database,
26the path is rebuilt or redownloaded.</para>
27
28<para>You can also scan the entire Nix store for corrupt paths:
29
30<screen>
31# nix-store --verify --check-contents --repair
32</screen>
33
34Any corrupt paths will be redownloaded if they’re available in a
35binary cache; otherwise, they cannot be repaired.</para>
36
37</section>