29 lines
1 KiB
Markdown
29 lines
1 KiB
Markdown
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# Nix Store Corruption {#sec-nix-store-corruption}
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After a system crash, it's possible for files in the Nix store to become
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corrupted. (For instance, the Ext4 file system has the tendency to
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replace un-synced files with zero bytes.) NixOS tries hard to prevent
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this from happening: it performs a `sync` before switching to a new
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configuration, and Nix's database is fully transactional. If corruption
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still occurs, you may be able to fix it automatically.
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If the corruption is in a path in the closure of the NixOS system
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configuration, you can fix it by doing
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```ShellSession
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# nixos-rebuild switch --repair
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```
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This will cause Nix to check every path in the closure, and if its
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cryptographic hash differs from the hash recorded in Nix's database, the
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path is rebuilt or redownloaded.
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You can also scan the entire Nix store for corrupt paths:
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```ShellSession
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# nix-store --verify --check-contents --repair
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```
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Any corrupt paths will be redownloaded if they're available in a binary
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cache; otherwise, they cannot be repaired.
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