[CentOS-devel] setting up an emergency update route

[Jeff Sheltren]

On Tue, Feb 3, 2015 at 12:58 PM, Karanbir Singh <mail-lists at karan.org>
wrote:
>
> repeated polling is counter productive. for the 6 times the high-prio
> push was needed in the last year, its a waste to destroy mirror cache's
> every 10 min through the entire year.
>

What cache are you referring to specifically (filesystem?, reverse proxy
cache? other?)?

Obviously the rsync method where each mirror pretty much "does their own
thing" is dated and not optimal.  The "hi, I just updated my mirror, here's
what I have currently" script portion of MirrorManager can at least help on
the polling side so that you have a more accurate and timely idea of which
mirrors are up to date.  Leveraging that, or similar, may be a small change
that could help move things in the right direction (and may or may not be
part of a long-term way to improve distro mirroring).

For starters, why not select a core group (10-20? Just making up a number
here, but get a good geographic/network spread) of external "tier 1"
mirrors and ask them to update more frequently (one hour seems reasonable
to me, and as an ex-mirror-admin I don't think that is asking too much).
And scan those more frequently (or use something similar to the
MirrorManager "I just updated" script) so that the status of those mirrors
is well known and they can be easily flagged if they are not being updated.

Non "tier 1" mirrors are asked to pull from the tier 1 mirrors, and are
asked to update at least every X hours.  I'm making the assumption that one
hour may be too frequent for some mirror admins, but perhaps push them into
updating at least every 2 or 3 hours.  These mirrors could be scanned for
status less frequently than the tier 1 mirrors because you know they will
be at least 2 hours behind or so.

Any other mirrors (not tier 1 or tier 2) are either dropped completely from
the official mirror list or are kept on a separate "we don't endorse these,
but here are some mirrors that may be fast for you to use, although perhaps
slightly out of date).

I think just that bit of shrinking the update window for mirrors could make
quite a difference.

I would argue that people who demand a faster update window than 3-4 hours
should look at a paid, supported alternative.  That said, I don't want to
use that as an argument against making the updates process as fast as we
possibly can.

-Jeff
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