GC strategy on clusters

[Ludovic Courtès]

Hi there!

Recently the Guix head node of our cluster at Inria was getting short on
disk space, despite running ‘guix gc -F20G’ (or similar) twice a day.

Turns out that some users had accumulated many profile generations and
that was getting in the way.  So we kindly asked them to run:

  guix package --delete-generations=4m

or similar, which was enough to free more space.

We’re now considering setting up automatic user notification by email,
as is commonly done for disk quotas, asking them to remove old
generations.  That way, users remain in control and choose what GC roots
or generations they want to remove.

How do people on this list deal with that?

Longer term, I think Guix should automatically delete old generations
and instead store the channels + manifest to reproduce them, when
possible.

Ludo’.