Hello, I've got some RHEL 4 systems I'd like to migrate to CentOS 4 but am not quite sure what all I need to do to make it successful. What I've done so far on my test system is:

rpm --import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-4

up2date --configure
Change noSSLServerURL to http://www.centos.org/XMLRPC
Change serverURL to https://www.centos.org/XMLRPC

Got rid of /etc/sysconfig/rhn/systemid

Successfully ran:

up2date centos-release yum centos-yumconf

Which caused it to load those as well as:

python-elementtree
python-sqlite
python-urlgrabber
sqlite

Finally, ran up2date -u and it installed:

comps
indexhtml
initscripts
redhat-logos


But I'm pretty sure I'm not completely done, for example, I still have
up2date-4.4.67-4 instead of up2date-4.4.50-4.centos4, and I still
have rpmdb-redhat-4-0.20060303 instead of rpmdb-CentOS-4.2-0.20051011

The production machines I want to migrate are running apache and Plesk
so I'm a little nervous about doing this until I am 100% sure what all needs
to change. We've been installing fresh servers using CentOS no problem,
so it's just these old boxes I want to move that worry me.

Thanks,

PD

Forgot to mention one other change I made up front. Edit /etc/sysconfig/rhn/sources
and comment out "up2date default" and add the following at the bottom:

yum centos4-Base http://mirror.centos.org/centos/4/os/$ARCH/
yum centos4-Updates http://mirror.centos.org/centos/4/updates/$ARCH/
yum centos4-extras http://mirror.centos.org/centos/4/extras/$ARCH/
#yum centos4-contrib http://mirror.centos.org/centos/4/contrib/$ARCH/
yum centos4-addons http://mirror.centos.org/centos/4/addons/$ARCH/
#yum centos4-centosplus http://mirror.centos.org/centos/4/centosplus/$ARCH/

You need to do

rpm -e --nodeps redhat-release

and then try

yum upgrade

You've done all this the hard way, by the way.

I downloaded the following from a CentOS mirror into an empty directory (in my case, they're on my USB memory stick):

centos-release-4-2.1.i386.rpm
centos-yumconf-4-4.3.noarch.rpm
python-elementtree-1.2.6-4.i386.rpm
python-sqlite-1.1.6-1.i386.rpm
python-urlgrabber-2.9.6-2.noarch.rpm
RPM-GPG-KEY-centos4
sqlite-3.2.2-1.i386.rpm
yum-2.4.0-1.centos4.noarch.rpm

Then ran:

rpm --import RPM-GPG-KEY-centos4
rpm -e --nodeps redhat-release
rpm -Uvh *.rpm

then

yum upgrade

I've done this without problems on three boxes so far.

Cheers,

Phil

Phil,

I'm moving from RHEL 3 (ES) to CentOS 4.3. I was going to use the CD's and choose the 'Upgrade' option but I'm worried how it'll turn out. Its on a mission-critical web server. Will your yum method above work for me?! What about using the CDs? Any good?

Thanks for any help you can give me, I've got to make the decision between RHEL or CentOS by tomorrow night when we install ;)



Devin

I would also be curious about moving from rhel3 to cent4.3.

-scoon

Why so, scoon? I decided to stick with Red Hat (we still have almost a year on our subscription) and upgraded from ES 3 to ES 4, Update 3 (essentially centos 4.3, no?) and it was seamless. All of my config files worked, though some needed to be renamed from .rpmsave. I did the upgrade the old fashioned way, via the CDs. The only problems I had were rather simple ones albeit strange, the upgrader installed the non-smb version of the kernel, limiting me to one processor on a dual core xeon system with hyperthreading. Downloaded the smb kernel from Red Hat and fixed that. Besides that, there was a strange problem where apparently 64bit versions of RHEL 4 are missing a kerboros5 file which broke pop3 and imap connectivity. Found the file online and installed it, now I'm running with no problem. Anyone having this problem, just telnet to your pop3 port and it will report on the missing file.

Devin

I too am curious about migrating RHEL 3 and/or 4 to Centos 4.3 ... Has anyone done so? I was assuming the safest way would be to put the ISO disks in and do "Upgrade" just like you'd do with a RHEL .... does anyone have any experience with this?

TedT

Phil,

Thanks for your post. After my student subscription expired, I was faced with paying out of my own pocket the fees for RHEL 4 upgrade subscription services. I tried Fedora Core 5, but it broke too my of my commercial software applicaitons. With your post, I was able to seamlessly switch over to CentOS. I liked the yumex uitlity in Fedora much better than up2date on RHEL. Now, I have the best of both worlds.

Thanks again,
Bruce

Quote:

Did you ever try this on your PLESK server?
I am about to. I will try it on two test machines. One without Plesk. Then one with Plesk installed.
Any advice will be helpfull.

I'd be very interested to hear some success stories on this method. We've currently got Apache, Postfix, Dovecot, Webmin, and possibly a few other things running on this server. Is it really just as simple as running this handful of commands that Phil has posted for us?

I wouldn't mind paying for Red Hat support as much if they offered a reasonable level of it. Either you pay through the nose and get average support or you pay a reasonable amount with a two-day response time. That's unacceptable.

I've thought of switching to other distributions entirely but the migration seems daunting and the time involved might be enough by itself to justify paying for the minimal level Red Hat support just so I don't have to be bothered with it..

Yesterday, I successfully migrated my RHEL 4 system to CentOS 4 using the procedure described by Phil above. There was one exception, however: I did not find the centos-yumconf package. Nevertheless, the upgrade went smooth as silk and was finished in less than 10 minutes. My environment is a typical LAMP-setup that includes Apache, MySQL and Perl. I've had no problems so far. I would recommend a full backup prior to upgrading though, e.g. using mondoarchive.

# Download rpm packages from a CentOS mirror of choice
RPM-GPG-KEY-centos4
centos-release
centos-yumconf
python-elementtree
python-sqlite
python-urlgrabber
sqlite
yum

# Import gpg key
rpm --import RPM-GPG-KEY-centos4

# Remove redhat dependencies
rpm -e --nodeps redhat-release

# Install the centos packages above
rpm -Uvh *.rpm

# Upgrade the installation
yum upgrade

Andreas
--

I would be interested too on the results of upgrading from RHEL3 to Centos4.
In fact, I am considering upgrading RHEL2 (with Oracle) to Centos4.

Does anyone foresee any problems?

Thanks,

Bill.