Re: Moving /gnu/store safely?

[Phil]

Thanks v much for the explanations.

Tobias Geerinckx-Rice writes:

> As gremlin's go this one is pretty tame, even cuddly: the Guix daemon
> deduplicates identical files, and creates hard links instead, saving a
> good amount of space.  That's all.
>
> By default, rsync does not preserve hard links (because of potential

Heh heh - yes I was surprised (and relieved) how quickly this gremlin
was dealt with just by scanning the manual and throwing some commands
together - this makes perfect sense so each hardlink just becomes a new file on 
the target.

I'm assuming the doubling in size is more fluke than by design?
i.e. there is no reason to assume each file is duplicated exactly once
in Guix?  It just turns out that hard linking was saving approx 50% by
chance in my specific store - it could have been 30% or 70% or whatever
and depends on your store contents?

> No, the links were *lost* and replaced by separate files during
> rsyncing.
>

Got it.  At the risk of speculating, would you expect the subsequent
execution of the garbage collector to deduplicate the identical rsync'd files
again?  I'm 100% clear on why the problem happened, just want to check I
understand why it went away which I ran 'guix gc'.

If I look at the link count on the files in my new /gnu/store I can see
some files have a count >1, which certainly suggests that Guix has
performed some sort of deduplication after the rsync?