gennerally its possible to upgrade from one minor release to the next
but not major releases so 5.1 to say 5.9 is possible but 5.x to 6.x is
not. you can attempt it through yum but you will have tons of
problems.

Fedora you usually can upgrade versions but even Fedora has version
cut offs where you have to do a scratch install for example 16 to 17
was one of those cutoffs.


On Mon, Jul 29, 2013 at 4:08 AM, Tom H <[log in to unmask]> wrote:
> 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.