Phil,

Barring unnoticed devils in details your process looks safe. 
Running ‘guix gc --verify’ is a good idea; add 
‘=repair[,contents]’ if you're paranoid.

Phil 写道：
> There were some gremlins tho - on restarting Guix the /gnu/store 
> was
> seen to grow to approximately double it's size.

[...]

>     rsync -va /gnu/store /some_other_disk/gnu/

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 pathological performance issues, IIRC).  This won't 
break /gnu/store: indentical files are still identical, they just 
take up more space.

To preserve them, you can use:

  -H, --hard-links
    This tells rsync to look for hard-linked files in the
    source and link together the corresponding files on the
    destination.  Without this option, hard-linked files in the
    source are treated as though they were separate files.

(I add ’-HAX’ as a matter of habit when making full-system 
back-ups.)

> I noted however that the new /gnu/store was approx double in 
> size - it
> looked like it had created new links to represent store items.

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

Kind regards,

T G-R