Amos Shapira wrote:
Is there a way to "freeze" a list of installed packages and exact versions, then tell yum (or any other tool/script) to install exactly these verions either on the same or another systme?
There isn't a need for an explicit feature. Just update one server, test it, then copy all of /var/cache/yum/updates/packages to the other machines. You can then say "rpm -Fvh *.rpm" in that directory to bring that machine up to the same level as the other one.
We don't do it exactly that way. We copy the current package cache to new machines after installation to speed a regular "yum update," as it needs only enough bandwidth to download what's changed since updating the package cache clone. Because of CentOS/RHEL's policy of not upgrading versions, only patching the released version, we haven't had any serious problems by allowing production systems to track the current yum repositories.