Chapter 4. Preparing for Installation

4.1. Preparing for a Network Installation

Note

Make sure no installation DVD (or any other type of DVD or CD) is in your system's CD or DVD drive if you are performing a network-based installation. Having a DVD or CD in the drive might cause unexpected errors.

Ensure that you have boot media available on CD, DVD, or a USB storage device such as a flash drive.

The Red Hat Enterprise Linux installation medium must be available for either a network installation (via NFS, FTP, or HTTP) or installation via local storage. Use the following steps if you are performing an NFS, FTP, or HTTP installation.

The NFS, FTP, or HTTP server to be used for installation over the network must be a separate, network-accessible server. It must provide the complete contents of the installation DVD-ROM.

Note

The Red Hat Enterprise Linux installation program has the ability to test the integrity of the installation media. It works with the DVD, hard drive ISO, and NFS ISO installation methods. We recommend that you test all installation media before starting the installation process, and before reporting any installation-related bugs (many of the bugs reported are actually due to improperly-burned DVDs). To use this test, type the following command at the boot: prompt:

linux mediacheck

Note

The public directory used to access the installation files over FTP, NFS, or HTTP is mapped to local storage on the network server. For example, the local directory /var/www/inst/rhel6 on the network server can be accessed as http://network.server.com/inst/rhel6.

In the following examples, the directory on the installation staging server that will contain the installation files will be specified as /location/of/disk/space. The directory that will be made publicly available via FTP, NFS, or HTTP will be specified as /publicly/available/directory. For example, /location/of/disk/space may be a directory you create called /var/isos. /publicly/available/directory might be /var/www/html/rhel6, for an HTTP install.

In the following, you will require an ISO image. An ISO image is a file containing an exact copy of the content of a DVD. To create an ISO image from a DVD use the following command:

dd if=/dev/dvd of=/location/of/disk/space/RHEL6.iso

where dvd refers to your DVD drive device.

To copy the files from the installation DVD to a Linux instance, which acts as an installation staging server, continue with either Section 4.1.1, “Preparing for FTP and HTTP installation” or Section 4.1.2, “Preparing for an NFS installation”.

4.1.1. Preparing for FTP and HTTP installation

Extract the files from the ISO image of the installation DVD and place them in a directory that is shared over FTP or HTTP.

Next, make sure that the directory is shared via FTP or HTTP, and verify client access. Test to see whether the directory is accessible from the server itself, and then from another machine on the same subnet to which you will be installing.

4.1.2. Preparing for an NFS installation

For NFS installation it is not necessary to extract all the files from the ISO image. It is sufficient to make the ISO image itself, the install.img file, and optionally the product.img file available on the network server via NFS.

Transfer the ISO image to the NFS exported directory. On a Linux system, run:
```
mv /location/of/disk/space/RHEL6.iso /publicly/available/directory/
```
Use a SHA256 checksum program to verify that the ISO image that you copied is intact. Many SHA256 checksum programs are available for various operating systems. On a Linux system, run:
```
$ sha256sum name_of_image.iso
```
where name_of_image is the name of the ISO image file. The SHA256 checksum program displays a string of 64 characters called a hash. Compare this hash to the hash displayed for this particular image on the Download Software page on the Red Hat Network (refer to Chapter 1, Obtaining Red Hat Enterprise Linux). The two hashes should be identical.

Copy the images/ directory within the ISO file to a directory named images/. Enter the following commands:

  mount -t iso9660 /path/to/RHEL6.iso /mnt/point -o loop,ro
  cp -pr /mnt/point/images /path/images/
  umount /mnt/point

Verify that the the images/ directory contains at least the install.img file, without which installation cannot proceed. Optionally, the images/ directory should contain the product.img file, without which only the packages for a Minimal installation will be available during the package group selection stage (refer to Section 9.17, “Package Group Selection”).
Ensure that the /publicly/available/directory directory is exported via NFS via an entry in /etc/exports on the network server.
To export a directory read-only to a specific system, use:
```
/publicly/available/directory client.ip.address (ro)
```
To export a directory read-only to all systems, use:
```
/publicly/available/directory * (ro)
```
On the network server, start the NFS daemon (on a Red Hat Enterprise Linux system, use /sbin/service nfs start). If NFS is already running, reload the configuration file (on a Red Hat Enterprise Linux system use /sbin/service nfs reload).
Be sure to test the NFS share following the directions in the Red Hat Enterprise Linux Deployment Guide. Refer to your NFS documentation for details on starting and stopping the NFS server.

Note

linux mediacheck