[packman] Mirror down

[Keith Hizal]

When ArchLinux was considering using Mirrorbrain and had this same worry,
the developer resonded as follows:

There can be more than one server - you could have a setup with failover
server, or actually run different servers on different continents. On
the other hand, openSUSE has been running with a single machine for over
two years now (due to regrettable lack of resources...), and other than
hard disk failures or human error, there were no issues with the setup.

That said, the best (and easiest) way to achieve failover would probably
be to run two servers (US, Europe) and use GeoDNS to distribute requests
geographically to them. If one goes down, just switch the clients over
to the other one by a little DNS change (keeping the TTL to 10 minutes or
so.) At the same time, such a setup has the advantage of giving clients
a faster response due to less roundtrip time.