Comment 8 for bug 317065

Opinion:
1) When compared to the cost of running the rest of the mirror infrastructure (such as EBS cost), the cost of traffic between zones is not a significant factor.
2) Using a traceroute method you could still end up with a bad server selection rather easily.

Question:
What's the best way to deal with failure scenarios? At RightScale we are looking at using a sources.list with all the mirrors in it. Starting with the 'round-robin' DNS which would give us balanced usage during package download. This does increase the download of index files (during apt-get update), however it also significantly increases the redundancy if one of the mirrors is down or unreachable. We preload the results from the first apt-get update onto the image so that it will minimize the impact on launch.

example snip:
deb http://ec2-us-east-mirror.rightscale.com/ubuntu_daily/latest intrepid main restricted multiverse universe
deb http://ec2-us-east-mirror.rightscale.com/ubuntu_daily/latest intrepid-updates main restricted multiverse universe
deb http://ec2-us-east-mirror.rightscale.com/ubuntu_daily/latest intrepid-security main restricted multiverse universe

deb http://ec2-us-east-mirror1.rightscale.com/ubuntu_daily/latest intrepid main restricted multiverse universe
deb http://ec2-us-east-mirror1.rightscale.com/ubuntu_daily/latest intrepid-updates main restricted multiverse universe
deb http://ec2-us-east-mirror1.rightscale.com/ubuntu_daily/latest intrepid-security main restricted multiverse universe
(and so on, for mirror2 and mirror3)