You've selected the packages to upgrade (or are performing an all at once upgrade), and started the process. The first thing to note is what packages are going to be removed. If one or more of them appear to be packages you need, cross-check them with the packages being installed to see if they are being replaced by a new package with similar functions. If they are not, make a note to follow the upgrade with a separate installation of whatever packages are required.
During a distribution upgrade, the system can generally remain in operation, although there will be slight disruptions when a package requires certain services to be restarted or libraries to be loaded.
These disruptions are more severe than a nonnal upgrade, particularly in cases where a package is removed and replaced with a different one to fulfill the same function, or removed because it is obsolete. Therefore, you may want to infonn users prior to the upgrade, and keep system activity to a minimum.
The next thing to watch for is the upgrade notes. Major changes are in how some software works are displayed (and e-mailed to the root account for later checking as well) in order to notify the installer of necessary post-installation steps to be taken.
Finally, when the administrator has made changes to the configuration of a package, the upgrade process will notify him/her of the non-default configuration and ask for help in resolving the differences. This involves leaving the current local version in place, replacing itwith the developers' version, or pausing the installation so the differences can be examined and resolved manually.
Often there are new options or defaults that should be added to the old configuration. Best practice is to either resolve the changes immediately, or keep the old configuration and cross-clteck it later with the new default
configuration (which is placed in the same directory with a modified name to keep it inactive but available for just this reason).
