OT yum rollback (was When will Fedora work again?)

Jerry Amundson jamundso at gmail.com
Thu Mar 12 16:15:35 UTC 2009


On Thu, Mar 12, 2009 at 10:37 AM, Seth Vidal <skvidal at fedoraproject.org> wrote:
> On Thu, 12 Mar 2009, David L wrote:
>> On Tue, Mar 10, 2009 at 8:38 AM, Patrick O'Callaghan wrote:
>>>
>>> On Tue, 2009-03-10 at 11:01 +0000, Frank Murphy (Frankly3D) wrote:
>>
>> <snip>
>>>>
>>>> Then would it be time for some sort of "rollback" utility,
>>>> so if "yum update something" breaks, maybe  : yum --rollback something
>>>
>>> That's been discussed before. It's fantastically hard to do, short of
>>> snapshotting the whole system.
>>>
>>>
>>
>> I saw this article that seems relevant to this discussion
>> a few months back:
>>
>> http://www.linux.com/feature/155922
>>
>> It talks about a "next generation" package manager called
>> Nix that claims to solve this kind of problem I think:
>>
>> http://nixos.org/
>>
>> Whether nix is for real or not, from a naive user's
>> perspective it sure seems like it should be possible
>> to solve this problem.  It basically seems like what svn
>> or other version control systems already do.  They
>> remember changes (and for the case of text files,
>> they store only differences.  For binaries it should
>> also be possible to efficiently store changes... in
>> fact I seem to remember a new update feature that
>> will do something like that).
>
> binaries are only half of the problem.
>
> You also have to worry about rolling back the users data.
>
> if I upgrade from mysql4 to mysql5, for example and get mysql5 running then
> my databases have been converted. Now, if I rollback the binaries, how do I
> go back?
>
> Mysql is obviously a big item and maybe not that common so let's look at a
> more common one:
> firefox
> evolution
>
> these two seem to routinely change their config formats in incompatible
> ways.
>
> How does a rollback solve that problem?

Except in extreme circumstances (e.g. MySQL) data files are a low
priority. If I'm in such dire straights to need a rollback, it's
because a package, or packages, is/are dead in the water. At that
point the data and/or configuration is moot.
So, I either
1. Wait for a fix.
2. Rollback.

Currently "2." happens manually anyway. By not having such a feature,
what is yum accomplishing?

jerry




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