Re: How to efficiently backup a bare repository?

[Junio C Hamano <gitster@pobox.com>]

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> There's no easy out of the box way to do exactly what you've
> described. A few things come to mind:
> ...

Wouldn't it suffice to have a cron job that runs something like

	D=$(date +"%Y-%m-%d")
	git fetch $serving "refs/*:refs/backup-$D/*"

on the back-up box to fetch from the repository on the box the
end-users push into once a day?  In the back-up repository, the
refs/backup-2018-11-25/heads/master reference would be today's tip
of the master branch of the serving repository.  You can set the
expiry timeout to "now" (i.e. "gc" will immediately drop unreachable
objects, and that is fine because you expicitly have refs to pin
these objects anyway), get the dedup from "git fetch" for free,
repack the backup repository as a whole, and dropping the whole
refs/backup-2018-10-25/* hierarcy on 2018-11-25 is all you need to
expire the refs.

You may want to play with the ref-advertisement limiting options in
the recent Git, if it is too much to grow the amount of "have"s by
30x for the common ancestry negotiation.  But that is a small
implementation detail.