Comment 6 for bug 361650

Curtis Hovey (<email address hidden>) wrote on 24 March 2010 18:57:
 >** Changed in: launchpad-registry
 > Milestone: 10.03 => 10.04
 >
 >--
 >launchpad could know about official country mirror status
 >https://bugs.launchpad.net/bugs/361650
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 >of the bug.
 >
 >Status in The Launchpad Registry: In Progress
 >
 >Bug description:
 >When the owners of a particular mirror request it, we will point DNS entries at their mirrors so they are official country mirrors (e.g. fr.archive.ubuntu.com, de.releases.ubuntu.com, etc.)
 >
 >Currently, if one of these mirrors degrades or fails, we are reliant on user reports informing us, so we can revert the DNS back to the main archive/releases machines.
 >
 >If Launchpad's mirror registry was able to indicate that particular mirrors are official country mirrors (and it could potentially be the case that a mirror carries more than one country's DNS entries), the mirror prober would be able to inform us of mirrors that should be disabled in DNS.

Automatic disabling of official country mirrors is dangerous because
the prober may *erroneously* think that a mirror is unavailable.

One example of misjudment happens when the international link between
the prober in Europe and the mirror fails. However the mirror may
still be accessible to national users. Since the majority of the
mirror users is usually from the same country, the mirror will be
performing its function pretty well even if it's inaccessible from the
prober in Europe. If you cut the country mirror out and send users to
another one, you'll just harm the users by telling them to go to a
usually slower site. Particularly if you point them to the main
machines in London.

It's better to let users tell you about unavailable mirrors than
trying to discover it from a single prober. You can minimize the risk
of keeping an unavailable mirror in the official country list by
assigning them only to reputable sites.