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The software vendor that we used has always specified that we should load RHEL on servers we've bought to run their software however they did start to accept CentOS and even now prefer it on new installs.

Anyway we have some servers running Red Hat Enterprise Linux Server release 5.3 (Tikanga) that have never had a RHN subscription, so basically they're exactly the same as what they were the day we loaded it.

Is it possible to convert these straight over to a new CentOS?

Edit: Ok so from reading more, it seems RHEL 5 can only be migrated to CentOS 5 and then I would need to do the updates to a newer version. It seems pretty straight forward, not even requiring a reboot. Here is the instructions I've found:

# cp /etc/redhat-release /etc/redhat-release-saved
# rpm -e --nodeps redhat-release-notes redhat-release yum-rhn-plugin redhat-logos
# rpm -ivh \
http://mirror.centos.org/centos/5/os/i386/CentOS/centos-release-5-8.el5.centos.i386.rpm  \
http://mirror.centos.org/centos/5/os/i386/CentOS/centos-release-notes-5.8-0.i386.rpm \
http://mirror.centos.org/centos/5/os/i386/CentOS/redhat-logos-4.9.99-11.el5.centos.noarch.rpm
# yum update

Is it really that simple to switch from RHEL to CentOS?

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  • Theoretically possible because the RPM's should be identical but I wouldn't chance it myself. – Bratchley Mar 13 '15 at 23:09
  • Also worth mentioning that you may want the 64bit versions. You have the 32bit versions referenced up there. – Bratchley Mar 13 '15 at 23:10
  • @Bratchley those instructions are from the CentOS website; would you still not attempt the switch? – SMW Mar 13 '15 at 23:14
  • We've done this at work with rhel 6.4 to centos. I'd google and test it first but what you have there looks like what we did. – user610209 Mar 13 '15 at 23:38
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    I've done it, and it's definitely possible. But as others noticed, it's going to be 5 => 5 only, and I don't think you can do 32bit => 64bit. – Aaron D. Marasco Mar 14 '15 at 0:08
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Not sure which pages you looked at, but the following page from the CentOS web site lists the steps, which looks roughly the same as what you have:

https://wiki.centos.org/HowTos/MigrationGuide

So, yes, it should be that simple.

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Many servers were successfully converted from RH5, RH6 to Centos, without a single failure.

  1. Access Centos Vaults. http://vault.centos.org/
  2. Are you using a 32 bit or 64 bit OS? http://vault.centos.org/5.11/os/
  3. Edit the repo - example given here: https://github.com/opsmason/centos-vault-yum-repos/blob/master/CentOS-Vault-Base.repo

baseurl - amend this from mirror to point at the Centos Vault:

baseurl=http://vault.centos.org/$releasever/os/$basearch/

baseurl=http://vault.centos.org/5.11/os/x86_64/

Even though, I've had no failures in the conversion - have a snapshot ready.

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