The generic linux x86 RPMs work with RH9. The way to tell if you support RPM is to ask yourself 'Do I Run Linux?'. RPM (Redhat Package Manager) runs on almost every GNU/Linux distro currently in production (yes, even slackware).

The reason I say to backup your databases is specifically so you can roll back. If you don't backup your DBs, once you upgrade, the DBs are converted to a new format incompatable with older versions.