11.5. Preparing for a Network Installation
Make sure an installation CD (or any other type of CD) is not in your system's CD/DVD drive if you are performing a network-based installation. Having a CD in the drive may cause unexpected errors.
The Red Hat Enterprise Linux installation media 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 machine which can provide the complete contents of the installation DVD-ROM or the installation CD-ROMs.
The Red Hat Enterprise Linux installation program has the ability to test the integrity of the installation media. It works with the CD / DVD, hard drive ISO, and NFS ISO installation methods. Red Hat recommends 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 CDs). To use this test, type the following command at the yaboot: prompt:
linux mediacheck
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 /export/directory. For example, /location/of/disk/space may be a directory you create called /var/isos. /export/directory might be /var/www/html/rhel5, for an HTTP install.
To copy the files from the installation DVD or CD-ROMs to a Linux machine which acts as an installation staging server, perform the following steps:
Create an iso image from the installation disk(s) using the following command:
For DVD:
dd if=/dev/dvd of=/location/of/disk/space/RHEL5.iso
where dvd refers to your DVD drive device.
For CD-ROMs:
dd if=/dev/cdrom of=/location/of/disk/space/diskX.iso
where cdrom refers to your CD drive device, and X is the number of the disk that you are copying, beginning with 1 for the first disk, and so on.
For FTP and HTTP installation, the iso image or images should be mounted via loopback in the publicly available directory, in the following manner:
For DVD:
mount -o loop /location/of/disk/space/RHEL5.iso /export/directory/
In this case /export/directory will be a directory that is shared via FTP or HTTP.
For CDROMs:
mount -o loop /location/of/disk/space/diskX.iso /export/directory/diskX/
Do the above for each of the CDROM iso images, for example:
mount -o loop /var/isos/disk1.iso /var/www/html/rhel5-install/disk1/
Next make sure that the /export/directory directory is shared via FTP or HTTP, and verify client access. You can check to see whether the directory is accessible from the server itself, and then from another machine on the same subnet that you will be installing to.
For NFS installation it is not necessary to mount the iso image. It is sufficient to make the iso image itself available via NFS. You can do this by moving the iso image or images to the NFS exported directory:
For DVD:
mv /location/of/disk/space/RHEL5.iso /export/directory/
For CDROMs:
mv /location/of/disk/space/disk*.iso /export/directory/
Ensure that the /export/directory directory is exported via NFS via an entry in /etc/exports.
To export to a specific system:
/export/directory client.ip.address(ro,no_root_squash)
To export to all systems use an entry such as:
/export/directory *(ro,no_root_squash)
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.