[CentOS] Migrate CentOS 3 to 4 to 5?

Ray Van Dolson rvandolson at esri.com
Thu Oct 25 15:23:20 UTC 2007

On Thu, Oct 25, 2007 at 05:32:46PM +0900, David Christopher Zentgraf wrote:
> The situation is as follows: Remote box at our host who offers CentOS  
> 3 as the most up-to-date OS, unless you pay them an unholy amount of  
> money for RHEL or Windows licences. Popping in a CD for an upgrade  
> does not work for us. We can and will have the OS restored to a clean  
> post-install state prior to updating. I have little intimate  
> knowledge with CentOS, RPMs or yum, but general good UNIX experience.  
> I know "live" yum migrations are greatly discouraged, but it seems to  
> work for people.

It _can_ work, although it might be a little messy.  I recently did a
FC3 -> CentOS 5 "upgrade" remotely.  It was a hassle.  Lotsa RPM's don't
play nice, and I had ended up trying to go from FC3 -> CentOS 4 the
first time around which obviously didn't work out too well so I
introduced some other issues by doing that (FC3 was the base for RHEL4
/ CentOS 4, so there are some versioning conflicts).  Ultimately I
think I upgraded the mess I made with that to FC4 and then to CentOS 5.

My best recommendation if you have no other choice is to remove as many
RPM's as you can -- get it as bare bones as possible.  Point your Yum
repo at the new repository and do a yum upgrade and see what errors you
come across.  Try and resolve, or just remove the offending RPM's.

In some cases I would either manually install an RPM to fix a
dependancy or rebuilt from an SRPM to add a Provides line at least to
get the upgrade going.  I didn't keep notes unfortunately on my
process, but it did take quite a while. :)  Eventually it did work

YMMV... maybe your colo would set you up with an IP KVM or something
temoprarily and you could do your own install?

And perhaps a CentOS 3 -> CentOS 4 -> CentOS 5 upgrade would work
better.  I'm sure others will comment.

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