On 03/26/2013 10:48 AM, wrote:

Sunday night I upgraded my server again – I had previously upgraded it from ubuntu 8.04 to 10.04, so I figured I’d go ahead and take it to 12.04 so it will be supported until 2017.

It all went smoothly. All I had to do to get the ball rolling was to type: ‘do-release-upgrade’ and the process began. Again, the box stayed up all through the upgrade, continued to serve dns and dhcp, routed nat traffic to the internet, and kept the vpns running.

When the upgrade was complete, I had to go to run level 6 to boot into the new kernel, so the system was down for about a minute while the reboot process ran its course.

When it came up, there was a problem with forwarding traffic to the internet. That was caused by a new /etc/sysctl.conf which didn’t have the ipv4 forwarding enabled. I fixed the file, typed “sysctl -p” to make the new setting take effect, and lan access to the internet was restored.

A bit later I noticed a second problem: wireless devices were not able to access the internet. I found that the dhcp server was not running. I tried starting it manually and it failed. Looking in the log, I could see that apparmor didn’t like the fancy things dhcpd was trying to do. Admittedly it’s a custom configuration, and the new version of dhcpd might require a few changes. At any rate, I just unloaded apparmor to get things up and running. Then dhcpd was able to start, and there were no other problems.

All in all, a smooth upgrade with a rather short outage.