The Medium: Where Is the Source Data?


The Medium: Where Is the Source Data?

When you install CentOS Linux, you copy operating system files from a sourcefrequently CDs or a DVDto the target computer's hard disk. There are two formats and many possible sources for the files.

Formats

CentOS Linux operating system files can be stored in two ways: as directory hierarchies on CDs, a DVD, or a hard disk; or as CD images or a DVD image on a hard disk (called ISO images after ISO9660, the standard defining the CD filesystem). Although the format is different, the content is the same. You can install CentOS Linux or burn CDs or a DVD from either format, although most people use the ISO images to burn CDs or a DVD because it is more convenient.

Sources

This chapter and the next provide information about installing CentOS Linux from CDs containing ISO image files or from a DVD containing a single ISO image file. The procedures are identical with one exception: When working with a DVD you do not have to change media during installation. These chapters do not cover installing from directory hierarchies; you use exactly the same techniques to install from a directory hierarchy as from an ISO image. Directory hierarchies are more cumbersome to work with than ISO images because they contain many files; each ISO image is a single file.

You can automate the installation using Kickstart (page ).

CDs or DVD

RHEL

CentOS Linux CDs are sold by Red Hat and its distributors. ISO images for CentOS Linux are available from Red Hat Network. To download these images, go to rhn.redhat.com, create an account if you do not have one, log in, click Channels on the menubar at the top of the page, click the name of the product you want to download, and click Downloads. The page that you download CentOS Linux from has instructions on how to download the installation or source disks. See also "" (page ) and "" (page ) for more information.

FEDORA

This book includes the DVD necessary for installing Centos Linux. Alternatively, you can purchase Centos Linux CDs or DVD from third-party vendors or you can download the Centos Linux ISO image(s) and install from the images or burn CDs or a DVD (next section).

Hard Disk

You can store ISO image files on the target system's hard disk if it is already running Linux. You need to burn only the first installation CD, the rescue CD, or the DVD (page ) to boot the system for a hard disk installation.

Network

You can use ISO image files located on a server system that the machine you are installing Linux on can connect to over a network during installation. You can use FTP, NFS, or HTTP for network installations. Unless you have a fast Internet connection, however, it is not advisable to perform an installation over the Internet because it can take a very long time; downloading ISO files is a more reliable and possibly less frustrating option. You need to burn only the first installation CD, the rescue CD, or the DVD (page ) to boot the system for a network installation.

You can also perform a remote network boot using PXE. See "" on page for sources of information on PXE.