This page addresses migration from older to newer CentOS versions, and from other Enterprise Linux distributions based on the same set of upstream source packages.
General considerations regarding migration:
A fresh install is generally strongly preferred over an upgrade.
- Be sure you have a good (bootable or restorable) backup before doing anything major to a system you care about.
- It is often helpful to have a bootable linux system on a separate set of partitions or better yet a separate disk. This can serve as a fall-back or rescue system, as well as an on-line backup. Disk space is cheap compared to sysadmin time.
Migration from other systems based on the same set of upstream source packages are relatively straight-forward. See FAQ/CentOS3 Question #5 “How do I migrate a system from WBEL-3 (White Box Enterprise Linux) to CentOS 3?” for example.
- You may want to upgrade the operating system parts of the filesystem and leave user directories, such as /home in place. If you do leave the old user home directories in place expect some problems with the GNOME/KDE menus and other desktop items. It may be preferable to create new user accounts and mount the old directories somewhere else in the filesystem for reference, copying, or linking user’s material after the migration.
Read more at wiki.centos.org