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Re: Building and caching old Guix derivations for a faster time machine
From: |
Ludovic Courtès |
Subject: |
Re: Building and caching old Guix derivations for a faster time machine |
Date: |
Thu, 16 Nov 2023 16:39:57 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
Hi,
Ricardo Wurmus <rekado@elephly.net> skribis:
> to me the biggest downside of using “guix time-machine” is that it has
> to do a lot of boring work before the interesting work begins. The
> boring work includes building Guix derivations for the given channels,
> most of which have long been collected as garbage on ci.guix.gnu.org.
>
> It would be helpful, I think, to more aggressively cache these
> derivations and their outputs, and to go back in time and build the
> derivatinons for past revisions of Guix. I would expect there to be a
> lot of overlap in the produced files, so perhaps it won’t cost all that
> much in terms of storage.
>
> What do you think?
I agree. The ‘guix publish’ TTL¹ at ci.guix was increased to 180 days
following <https://issues.guix.gnu.org/48926> in 2021. That’s still not
that much and these days and right now we have 84 TiB free at ci.guix.
I guess we can afford increasing the TTL, probably starting with, say,
300 days, and monitoring disk usage.
WDYT?
For longer-term storage though, we’ll need a solution like what Simon
described, offered by university colleagues. I’m not sure why this
particular effort stalled; we should check with whoever spearheaded it
and see if we can resume.
Thanks,
Ludo’.
¹ That’s the time-to-live, which denotes the minimum time a substitute
is kept. Anytime a substitute is queried, its “age” is reset; if
nobody asks for it, it may be reclaimed after its TTL has expired.