Jegadeesh Kumar <jegasmile at yahoo.com> writes: > I wan to know the details steps about how to do OS upgrade? > Say for an example currently i am using CentOS 6.2 and plan to upgrade > that to 7. Please detail me the steps. I suggest you begin by reading the release notes for CentOS 7, which are at http://wiki.centos.org/Manuals/ReleaseNotes/CentOS7 -- here is an excerpt: For the first time, there is a supported upgrade path from CentOS-6 to CentOS-7. This path is only supported from the latest version of CentOS-6 (being 6.6 at the time of writing) to the latest version of CentOS-7. For more information on the upgrade procedure please take a look at this page. The tools needed for this functionality are still being tested and will be released at a later time. If you can help with the testing, please see this CentOS-Devel mailing list thread and this wiki entry. So, upgrade to 6.6 first, and then use the upgrade procedure from Red Hat, if you're willing to help with testing. Or install 7 from scratch, of course.