"upgrading ubuntu to debian"

[Shachar Shemesh]

geoffrey mendelson wrote:
> I am currently running Ubuntu 9.04. I am fed up with it. I want to 
> replace it with debian, hopefully without wiping the hard drive in the 
> process.
>
> I looked around and found an Israeli mirror but there are something 
> like 31 cd's or 5 dvd's and updates. Is there a simple way to upgrade 
> it it, like changing the sources file for apt and doing a dist-upgrade?
>
> If not what do I download and what do I do with it?
>
> Note that I have 2 systems to upgrade and is there a way to not have 
> to download everything twice?
>
> I have a fast enough Internet connection that I could download the DVD 
> images one per night while I am sleeping and burn them to DVD's during 
> the day if need be.
>
> If I use jigdo instead of a straight download do I get custom dvd's up 
> to date, or the same ones as if I dowloaded the release images?
>
> Thanks in advance for any advice.
>
> Geoff.
>
Ok, let's try to answer all questions.

First - you do not need to download everything. You can perform a 
complete Debian install with no more than the first CD. You would still 
need to download certain stuff from the internet, but this is a small 
amount in comparison. Most everything you need is on the first CD.

If you already have an APT system set up, you can use a tool called 
"apt-proxy". If you put that as your apt source, it will cache the 
packages you download. This way, you can perform a full network install, 
and yet not download anything twice. This is the most compact (download 
wise) setup you can do. With only two systems, I'm not sure it is the 
most efficient, however (especially since one of those system will need 
to be the proxy, obviously).

Turning an Ubuntu 9.04 system into a Debian system (you didn't say 
whether it is Unstable, Testing or Stable) is, likely, not possible 
using only apt operations. One thing you can do is use debootstrap to 
setup your debian system in a new partition, and then switch over to it. 
Not for the novice, but the most difficult parts are getting the kernel 
and boot loader into system, so not brain surgery either.

If you decide to go the CD/DVD route, it doesn't matter how you 
download. Jigdo will not give you more up to date image than the latest 
ISO. You can use jigdo in combination with apt-proxy, so it is not 
totally useless (I always use jigdo for downloads, mostly because it 
allows "upgrading" an older image, or from the i386 to the amd64 image, 
without re-downloading everything from scratch).

The easiest is if you have a separate home partition. Just reinstall the 
base system, leaving the home partition alone. There will be some 
tailoring to do (versions don't match exactly, you will not remember to 
install all packages from the get go, etc.). When I do such transitions, 
I always save the old etc directory somewhere, so I can pick up things I 
forgot later on.

Good luck

Shachar

-- 
Shachar Shemesh
Lingnu Open Source Consulting Ltd.
http://www.lingnu.com

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