[rhn-users] RHEL AS21 to AS3 upgrades (up2date or reload?)

[Doerbeck, Christoph]

Greetings all,

I'm faced with the challenge of upgrading a bunch of RHEL AS21 hosts 
to AS3.  Instinct and years of practice (wisdom?) steer me to reload the
hosts
with AS3 where ever possible.  However, in certain cases ...  being
able to use up2date or some other scripted mechanism is very attractive
to migrate a RHEL AS21 host to AS3 (due mainly to level of
customizations
that went into application installs).

Is there any experience on this mailing list regarding this?

Off the top of my head, items of concern are:
	+ device driver name and/or parameter changes (modules.conf)
	+ initscript modifications that may get lost (rc.sysinit (vxvm))
	+ filesystem updates (meta-data structure changes requiring
updates
		which could potentially thwart backouts?)
	+ changes in kernel parameter names/values (ex: sysctl.conf,
fs.file-max
		in AS21 is pretty low and required parm change, but
default in AS3
		is sufficient in most case and leaving AS21 config in
place	
		would be counter productive.)
	+ /boot partition may not be of sufficient size (old AS21
kernels
		would need to be removed (versus left behind alla
upgrade)
	+ Something of concern are the junk files which packages (RPMs)
don't 
		capture and	and upgraded boxes seem to always
collect in droves.  
		Are there any obvious files/directories anyone is
familiar with?

Thanks for any feedback.

Christoph