[Nix-dev] Nar doesn't support hardlinks? (was: [NixOS/nixpkgs] 1f2228: tzdata: use symlinks instead of hardlinks)

[Shea Levy]

On Tue, Apr 29, 2014 at 04:34:59PM +0200, Peter Simons wrote:
> Mihaly Barasz writes:
> 
>  > tzdata: use symlinks instead of hardlinks
>  >
>  > Hard links are not handled by nar, so installing from binary cache
>  > unnecessarily duplicates data.
> 
> Huh? Nar archives cannot handle hardlinks? That comes as quite a
> surprise to me. Are you sure about that?
> 

This is correct, nix's filesystem abstraction doesn't have room for
hardlinks (they get unlinked in a serialization roundtrip). This is of
course semantically fine since everything is read-only, but it does have
implications for hard links to save space, which is why nix-store
--optimize exists.

>
> Best regards,
> Peter
> 
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