On Thu, Jul 25, 2013 at 12:48 PM, Lamar Owen <[log in to unmask]> wrote:
> On 07/25/2013 01:28 AM, David G.Miller wrote:


>> The problem of upgrading from FC-n to FC-n+1 is basically the same as
>> upgrading EL-n to EL-n+1.
>
> No; upgrading ELx to ELx+1 is like upgrading Fn to Fn+k(x), where k(x) is an
> element of an array of integer constants; x is the starting EL release, so
> k(3)=3 [RHEL3 was based on what I'm going to call 'Fedora Core 0,' which was
> the pre-fedora RHL 10 beta; see footnote 1]; k(4)=3, k(5)=6 (or 7, since
> some F13 packages showed up in EL6), and k(6) will probably be 7 or so.
>
> Doing this without going stepwise through the Fedora releases is a
> challenge. I forget how large of an increment preupgrade can do, but I
> remember doing it F12 to F13 to F14, and it had issues even going Fn to
> Fn+1, especially if any part of the massive yum transaction fails for any
> reason (it leaves the system with a half completed yum transaction that
> yum-complete-transaction simply won't deal with, and then you have to finish
> the upgrade manually and manually remove the older packages).... I have done
> this twice on two separate machines, one had issues going from F12 to F13
> and the other one had issues going from F13 to F14. The Fn to Fn+1 upgrade
> path is somewhat expected to work; Fn to Fn+2 probably won't work correctly,
> especially if major changes are in both releases.

In theory, preupgrade can upgrade a system to the latest Fedora
release; I assume from a still supported release so it's Fn to Fn+2. I
have a colleague who went on his laptop from 12 to 14 and you can find
people skipping a release on mailing lists and forums. But they're
there because they have a problem. :) Both preupgrade and fedup are
the source of quite a few list and forum posts.

A more usable upgrade system would be one where you could snapshot a
system transparently before an upgrade and fallback to the original in
case of failure, like Solaris with its "Boot Environment".


> In the Ubuntu world, this is like taking Ubuntu LTS 6.06 straight to 8.04,
> or worse. I've done the 6.06 to 8.04 thing, by the way, and have no desire
> to repeat it.

Ubuntu/Canonical support LTS-to-LTS upgrades (6.06 to 8.04 to 10.04 to
12.04) where intermediate versions are skipped (so they must be QAd
quite extensively; and companies with support contracts must be
on-hand for all phases of the upgrade). I've tested an 8.04 to 10.04
upgrade (as I've tested preupgrade and fedup upgrades) but I've never
used Linux upgrades in a live/production setting.