Trying to yum upgrade 19 is stuck on a mirror with no useful throughput. What kind of workaround for this is available? Nothing jumps at me in the yum man page. How do I specify to use a particular mirror know to work?
If the speed is below some threshold, yum should blacklist the mirror and use a different one next time. If you don't have the patience, try hitting Ctrl+C during the download. Ideally this should switch to a different mirror (but I'm not sure if this functionality wasn't removed).
Of course, you can also edit /etc/yum/*.repo and hardcode some fast mirror near you: https://mirrors.fedoraproject.org/
But that doesn't guard you against outdated mirrors, and doesn't provide fallback if your chosen mirror is down.