These are my links for 23 lug 2015 from 17:27 to 17:47:

• How to fix yum errors on CentOS, RHEL or Fedora – Xmodulo – Yum is a package management tool for installing, updating and removing rpm packages on RedHat-based systems. When you try to install a package with yum command, you may encounter errors for various reasons. In this post, I will describe under what situations yum errors can occur, and explain how to fix yum errors.
• Docs/RpmRecovery – rpm – Trac – This document provides an overview of how to deal with RPM database corruption.
• RepoCreate – yum – Trac – Sometimes you'll find you need to be able to collect a bunch of rpm packages you have together in one place and you want to make them available to your systems running yum. It is pretty easy to do.
• Local YUM fun | Adamish | Blog – If you’re installing redhat on a machine without Internet access you may wish to setup a local YUM repository for extra bits and pieces after the main install. Add the following to /etc/yum.repos.d/local.repo. If there are any other .repo files in /etc/yum.repos.d then comment out their contents. Make sure you don’t have spaces in your baseurl.
• How to fix yum [Errno -1] Metadata file does not match checksum › Backdrift Backdrift – I recently upgraded my local yum repository server to RHEL6. After upgrading I noticed the below error when my el5 clients would attempting to install packages from the local repo with yum.