I've got some low-traffic web sites on a Linode running Ubuntu 8.04. It's (long past) time to upgrade. I'm skeptical that doing this in place, going all the way to 12 is a good idea.

What's the right way to collect together apache configs, site content dirs, iptables, nagios and other stuff and get them off the linode, then destroy it and build a new one, then reinstate as much as I can as painlessly and quickly as I can? Any tutorials that walk through considerations?

Thanks.

Spin up a new linode with 12.04, copy over all your configs, then swap IP's to the new one. Billing is pro-rated to the day, so if you get it done in a day or two, it only costs a couple bucks assuming a 1024 (note that you do pay up front for the month, but you'll get back a credit when you destroy the old one).

I agree with glg, put the "build" step before "destroy" so you're preparing the 12.04 node in parallel with the existing node and only cutting over once everything looks good. Depending on the amount of dynamic state (e.g., databases or data files) you may have some small amount of actual down time while you transfer over the final updates, but it'll be as short as possible (and less risky). You can also run parallel tests to ensure that nothing has broken with all the various packages that may be running later versions.

While I have nodes in a similar state and also plan to migrate by installing 12.04 anew, I wouldn't necessarily discount the in-place upgrade if that might be easier. Though I think you have to do 10.04 first and then 12.04. But a second node is a great test case for that too. Create the node and then clone your current node to it[*] (or if you have backups enabled, use a snapshot to avoid any down time). Then give the upgrades a shot. Worst case it doesn't work (or is more complicated than you want) and you just go back to starting with a new install and bringing over the configs by hand.

-- David

[*] Remember to use rescue mode to tweak any external facing tasks or configurations (like host name) that might be inherited from the production node but you don't want running on the second box.

Indeed, you can upgrade directly between LTS releases, but you can't jump over 10.04, that has to be the intermediate step.

Thanks for all your help, folks. I'm going to do both: clone, make modifications to mitigate the cloning, boot the clone and upgrade the clone in place from 8.04 to 10.04 then from 10 to 12. If it all works, I change DNS to point to the upgraded clone and I'm done. If it doesn't, I do the configs by hand, then change DNS then finally hose the old Linode when some backups accrue on the new one.

EDIT: swap IPs is what I actually meant by change DNS.