Re: Downgrading?
It can be done, but your package lists will get cabbaged. I did it on
a workstation once, and within a year, the machine was
unmaintainable...Especially when upgrading to the new stable (e.g.
lenny to squeeze). It had all sorts of extra hoops to jump through...
Having done it, I would concur with those that say back up and do a
fresh install.
--b
On Fri, Feb 3, 2012 at 4:02 PM, Bob Proulx <bob@proulx.com> wrote:
> Julien Claassen wrote:
>> I just wondered, if it would be possible to downgrade my Debian
>> distro from - say - Wheezy to Squeeze? I thought, that it must work,
>> but I can't for the life of me think, which exact command to use.
>
> No. That operation is not supported. It would be almost impossible
> to test all of the cases. And the need for doing so is much rarer.
> Upgrading is a task that everyone needs, at least for security
> upgrades. But downgrading is uncommon.
>
> An individual project package might downgrade just fine. But taking
> the entire system back would be very unlikely to be completely
> successful.
>
> The problem comes down to migration of configuration files and
> migration of system configuration. When upgrading the postinst script
> is coded to transition forward in time from older formats to newer
> formats. And if there is a particularly troublesome problem at some
> revision then specific cases can be coded around. The newer package
> knows about the problems that were created in the older package.
>
> Downgrading is the opposite case. Now the older package would need to
> know how to back out things that happen in the newer package. But at
> the time that the older package was written the newer package had not
> been created yet. Therefore in the general case it is impossible for
> the older package to be able to handle all potential issues.
>
> For packages without any configuration files or anything except
> executables in /usr/bin and documentation in /usr/share/doc the
> downgrade will be trivial and will always work as expected. But for
> other more complicated packages it might be required to purge,
> re-install, then reconfigure.
>
> Over the entire system from something with as many changes as going
> from Squeeze to Wheezy and then back this would be impossible. Take
> for example the scripts that convert to the new tmpfs /run
> configuration. All of that would need to be undone. That is too much
> to ask.
>
> Bob
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