On Sat, Jul 23, 2011 at 8:58 PM, Thomas Dukes <tdukes at sc.rr.com> wrote: > Red Hat does not support upgrades between major versions (doesn't necessarily mean it's not possible) > http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/ch-upgrade-x86.html > http://linsec.ca/blog/2011/02/23/my-adventure-upgrading-rhel5-to-rhel6/ > > Since when?? I started with slackware 1.0 on a pentinum 1 system from VaResearch back in the mid 90's, change to Redat 2.0, then Fedora, then to Whitebox, then CentOS.. Never had a problem upgrading on an rpm based system. That's a good question. It seems that since RHEL 4 (2005), Red Hat has been telling us that upgrading from earlier major versions is not a good idea. - RHEL 3 docs say it's possible to upgrade from 2.1 to 3.x (http://goo.gl/8Gwrs) - RHEL 4 docs don't bother showing the steps and provide a lot of warnings for 2.x/3.x to 4.x (http://goo.gl/yiRGK) - RHEL 5 docs explicitly say Red Hat does not support upgrading from earlier major versions (http://goo.gl/RQABB) - RHEL 6 docs explicitly say Red Hat does not support upgrading from earlier major versions (http://goo.gl/H9zBU) I don't think RPM is the one allowing/disallowing the upgrade between major versions. The kernel architecture and other major components changes are more likely to be the culprit. I'd be surprised how you moved from Slackware 1.0 all the way to CentOS without a reinstall (because that's what is being discussed here). Just as reference, starting with Solaris 11, it'll not be possible to upgrade from earlier major versions either (although binary compatibility will still be there). Oracle is asking customers to treat earlier versions as legacy and put them in containers and/or virtual machines. Solaris 11 will change so much how things work that Oracle says it's better not to bother upgrading path from Solaris 10. My point is that big changes happen in Linux much frequently than in Solaris and even Solaris sometimes doesn't support these kinds of upgrades. -- Giovanni Tirloni