rpm rollback features...

[James Olin Oden <joden lee k12 nc us>]

Hi All,

I have been looking at RPM's transactional rollback features
and I what I believe is a basic understanding, but I am 
fuzzy on some points and would like some guidance.  Also,
I may be assuming I understand whereas I do not truly, so
I would like to re-iterate what I think I understand...understand? (-;

	- Transactional rollback capabilities are in the 
	  RPM 4 series and only really became workable 4.04.
	- As RPM's are installed or upgraded the image of 
	  the header of each rpm is stored away somewhere.
	- Also, when RPM's are installed as a group (even a
	  a group of one), a TID (transactional ID) is assigned
	  to this group of rpm's and the TID is time stamped 
	  (I assume in some relational way but the implementation
	  is not important).
	- When doing an upgrade or an erase of an rpm 
	  one can use the --repackage switch and all the compents
	  of the package as they are currently installed onto the
	  system and the saved package header will be stuffed 
	  back into a package which will be created in the
	  directory defined by %_repackage_dir.
	- Their is a mysterious --rollback switch in the source
	  that has something to do with all this (-;

What I am not sure about (other than the last statement (-;), is 
what is the prefered method of:

	- rolling back one package to a saved previous package.  That
	  is you did the upgrade with --repackage, you realized you
	  really did not want that upgrade, and now you want to install
	  the old package.  What is the "correct" way of doing that?
	- You have a group of package that you wish to roll back to
	  what is the prefered method of doing this? 

Lastly just some questions:

	- what are the things to consider when building packages that
	  will not hinder a rollback/backout (I have some ideas,
	  but I would like to hear others)?
	- How does rpm handle the scriptlets in a backout situation?
	- Are there any docs (other than source, but I am trying to 
	  parse through them) for these features (also, I know of the
	  tiny mention in the man page)?

Thanks for any and all answers...james