When I started what I thought would be a simple update of a few of my Ubuntu server virtual machines I didn't know how much trouble the mirrors would give me.
For a start, the sg. mirror failed to load completely. Then I found some info about ec2 mirrors, but they gave me Hash Sum mismatch problems.
Then I came across the mirror:// schema, that worked great and I managed to upgrade one system. Funny enough, I would expected the upgrade from 10.04 to result in a 12.04 but I ended up with 11.10?? Not so sure if I started with a different version or the failed update and upgrades caused this.
Now my problems really started. Trying to upgrade from 11.10 Oneric to 12.04 Precise seemed impossible. If I would use the mirror://mirrors.ubuntu.com/mirrors.txt the mirrors would fail and no package information was downloaded. Next, using the ec2 it wouldn't even try to download as the Hash would fail.
In the end I logged into a Ubuntu server I manage in the Netherlands and download the http://mirrors.ubuntu.com/mirrors.txt. This is the list I downloaded from the Netherlands:
http://ftp.telfort.nl/pub/mirror/ubuntu/ http://ubuntu.mirror.cambrium.nl/ubuntu/ http://ftp.snt.utwente.nl/pub/os/linux/ubuntu/ http://nl3.archive.ubuntu.com/ubuntu/ http://nl.archive.ubuntu.com/ubuntu/ http://ubuntu.mirror.atratoip.net/ubuntu/ http://ubuntu.tiscali.nl/ http://osmirror.rug.nl/ubuntu/ http://mirror.nl.leaseweb.net/ubuntu/ http://mirror.i3d.net/pub/ubuntu/ http://ftp.tudelft.nl/archive.ubuntu.com/ http://mirrors.nl.eu.kernel.org/ubuntu/
Compared to the one from Singapore:
http://linux.ntuoss.org/ubuntu/ http://mirror.nus.edu.sg/ubuntu/ http://download.nus.edu.sg/mirror/ubuntu/ http://ubuntu.oss.eznetsols.org/ubuntu/ http://archive.ubuntu.com/ubuntu/
The tudelft seemed the most reliable source and when I replaced my mirrors with this one I managed to finally upgrade the server to 12.04.
So much for Ubuntu being the most user friendly Linux distro around. And shame on the mirrors in Singapore for being of such poor standard.