Upgrading from Previous Releases
This section explains how to upgrade to FreeBSD 6.2 from a previous FreeBSD release. There is a separate section of this guide for applying updates to an already installed FreeBSD 6.2 system.
The BSDs are unique in the operating system world because they are generally upgraded "in place" by updating the source code, recompiling the entire operating system, restarting the computer in single user mode to install the new system, and then restarting again in the updated environment. It's completely possible to do this on a production system and suffer very little downtime, though it's of course preferable to try everything on a test server first to make sure that there aren't any hidden or latent problems.
If you prefer, it's possible to do a clean install as well, meaning you erase what is currently on the hard drive or disk slice and install a fresh FreeBSD environment. This of course means losing all of your custom settings and—unless it's on a separate disk or slice—data, so this scenario is more time-consuming and in general less friendly to production environments.
A clean install means reinstalling FreeBSD from scratch. This process is identical to the standard installation, so if this is what you want to do, follow the normal installation instructions printed above. The directions in this chapter refer to an in-place upgrade.
Performing an in-place upgrade to FreeBSD 6.2 is best done from FreeBSD 6.1. The further away you are from 6.2, the greater ...