[CentOS-mirror] AltArch mirror geographical coverage, need more mirrors outside US/EU

Hi, we're looking to extend the geographical coverage of CentOS AltArch
mirrors a bit. For those who don't know, the Alternative Architecture
SIG produces CentOS 7 for all kinds of odd architectures such as
aarch64, armhfp, i386, power9, ppc64 and ppc64le.

We have a separate list of mirrors providing AltArch content at
https://www.centos.org/download/altarch-mirrors/ and if you have a look
at that list, you will notice that there are several mirrors from Europe
and U.S., but less from other regions.

We're currently in the process of shifting AltArch-related traffic from
mirror.centos.org to external mirrors. Most of those mirror.centos.org
nodes double as msync nodes, and by directing users to use external
mirrors instead of mirror.c.o, more bandwidth would be available for
syncing external mirrors. In addition to the saved bandwidth, many of
the external mirrors have much more bandwidth than msync.c.o nodes, so
the end users will also see a benefit.

If the existing AltArch mirrors have a look at their traffic stats, they
will probably notice that there hasn't been much AltArch traffic. That
will see a slight increase soon, though. We will soon push out updated
centos-release packages for AltArch that will use mirrorlist.c.o to find
a nearby external mirror, instead of the currently configured
mirror.centos.org. The old mirror crawler only checked main architecture
repos (and only a subset of those), but the current mirror crawler will
check main architectures and AltArch architectures, and all the
repositories that are active.

Some AltArch .iso download links have also been changed to point to
isoredirect.c.o, which has a newly added capacity to redirect AltArch
.iso image requests to external mirrors. The remaining AltArch .iso
redirects to external mirrors will be done prior to CentOS 7.6.18xx release.

That said, I don't expect AltArch to generate significant additional
traffic compared to the main architectures. My primary concern here is
the geographical coverage, ie. the number of countries represented.
Let's say that it'd be nice if there were mirrors from a handful of
countries from each continent.

If there isn't yet an AltArch mirror in your country and you think your
mirror could close a "gap", please consider mirroring AltArch as well.
At the moment AltArch consumes around 100 GB of disk space. Please note
that when CentOS 7.6.18xx gets released, both 7.5.1804 and 7.6.18xx will
be kept on mirrors for a while, thus temporarily doubling the disk space
required.

Another technical point is that if you start mirroring AltArch, the
content must be available in a different directory (and thus at a
different URL) than the main content. One common convention is to have
directories "centos" and "centos-altarch". You will also need to invoke
rsync twice; first for the main content (as before) and then for the
AltArch content at rsync://msync.centos.org/altarch/

Although all current CentOS mirrors can already access the above
msync.c.o module for AltArch, it would be nice if you could do your
initial rsync from some other external mirrors listed on
https://www.centos.org/download/altarch-mirrors/ , even if the nearest
external mirror providing AltArch over rsync isn't exactly nearby. Once
you have done an initial sync from an external mirror, you can switch to
doing incremental syncs from rsync://msync.centos.org/altarch/

Once you are done, please provide the http/https/rsync URLs to your
mirrored AltArch content so those could be added to the list.

Thanks for reading this far, and thanks for all the bandwidth!