[CentOS] RHEL-6 vs. CentOS-5.5 (was: Static assignment of SCSI device names?)

Sun Jan 30 22:07:59 UTC 2011
Nico Kadel-Garcia <nkadel at gmail.com>

On Sun, Jan 30, 2011 at 2:37 PM, Chuck Munro <chuckm at seafoam.net> wrote:
> Hello list members,
> My adventure into udev rules has taken an interesting turn.  I did
> discover a stupid error in the way I was attempting to assign static
> disk device names on CentOS-5.5, so that's out of the way.
> But in the process of exploring, I installed a trial copy of RHEL-6 on
> the new machine to see if anything had changed (since I intend this box
> to run CentOS-6 anyway).
> Lots of differences, and it's obvious that RedHat does things a bit
> differently here and there.  My focus has been on figuring out how best
> to solve my udev challenge, and I found that tools like 'scsi_id' and
> udev admin/test commands have changed.  The udev rules themselves seem
> to be the same.
> Regarding networking, all of my 'ifcfg-*' files from CentOS-5.5 worked
> well, including bridging for KVM.  Of course, one of the first things I
> did was remove that atrocious NetworkManager package ... it needs to be
> rewritten to make it a *lot* more intuitive.  RedHat uses it during
> installation to manually configure the NICs, which I think is a
> mistake.  I much prefer the way CentOS anaconda has done it so far, as a
> separate install menu form.

Unfortunately, working out all the dependencies and preventing it from
activation is more tricky. I suggest putting "NM_CONTROLLLED=no" in
all your /etc/sysconfig/network-scripts/ifcfg-* files, it just makes
the whole thing a lot safer for server class installations. I don't
know if it's more stable or workable in the latest Fedora releases,
but I'm still unhappy with it in CentOS and RHEL.

> The performance of the machine seemed to be better with the newer
> kernel, which is encouraging.  I suspect we can look forward to a number
> of improvements.  I've just managed to scratch the surface.  I do expect
> there may be a few challenges for those of us upgrading a system from
> 5.x to 6, where some user-written admin scripts could break depending on
> the system commands they use.

Ohhhhh, yes. This is inevitable with OS updates this far apart: just
the switch from the default sendmail and syslog to postfix and rsyslog
caught me somewhat by surprise.