[CentOS] Re: centos] RPM Autorollback

Thu Jul 14 01:46:07 UTC 2005
R P Herrold <herrold at owlriver.com>

On Wed, 13 Jul 2005, James Olin Oden wrote:

> On 7/13/05, R P Herrold <herrold at owlriver.com> wrote:

>> it scarcely matters -- rpm rollback is a essentially
>> unattainable mirage, due to the unbounded nature of %pre and
>> %post actions possible.
>>
> I wouldn't go that far (though obviously I understand the issues from
> the previous email).   My goal with autorollback and a few patchs to
> the regular rollback code was to make it possible to rollback
> (automatically) a failed upgrade.  That said scriptlets may in some
> cases need changing to work properly/intuitavily in a
> rollback transaction.

and within that limited scope, it may well work.  I can easily 
think of the circumstance that is does not -- the 'upgradeany' 
transition from (RHEL|CentOS-)3 [2.4 kernel, modutils, and 
friends] to (RHEL|CentOS-)4 [2.6, etc] is a one way trip as to 
the general, used for a while install, case, in almost all 
circumstances.

In a narrow scope, with strong Change Management, and defined 
Sepcifications and Requirements, it should be possible to 
audit and stabilize the relevant scriptlets.  Say I was 
rolling out 20k units in a telephony control application, 
** without on-host end user level application services needed 
**, it could be done.

But in working through a cost-benefit analysis recently on a 
project of similar scale, I think I pretty throughly convinced 
the proponent of a 'rollback' approach, that I could 
automatedly rip out and re-provision and re-configure more 
consistently, cheaper, and quicker, than the 'rollback' based 
approach.

It is a fascinating area, JOO is well respected by me for his 
work in this field, and this topic has been hashed in more 
detail on the RH hosted rpm-list, and the Duke hosted 
rpm-devel mailing lists, for those intersted in more detail.

- Russ Herrold