Chapter 4. Diskless Environments
Some networks require multiple systems with the same configuration. They
also require that these systems be easy to reboot, upgrade, and
manage. One solution is to use a diskless
environment in which most of the operating system, which can
be read-only, is shared from a central server between the clients. The
individual clients have their own directories on the central server for
the rest of the operating system, which must be read/write. Each time the
client boots, it mounts most of the OS from the NFS server as read-only
and another directory as read-write. Each client has its own read-write
directory so that one client can not affect the others.
The following steps are necessary to configure Red Hat Enterprise Linux to run on a diskless
client:
Install Red Hat Enterprise Linux on a system so that the files can be copied to the
NFS server. (Refer to the Red Hat Enterprise Linux Installation Guide for
details.) Any software to be used on the clients must be installed on
this system and the busybox-anaconda package
must be installed.
Create a directory on the NFS server to contain the diskless
environment such as /diskless/i386/RHEL4-AS/. For
example:
mkdir -p /diskless/i386/RHEL4-AS/ |
This directory is referred to as the diskless
directory.
Create a subdirectory of this directory named
root/:
mkdir -p /diskless/i386/RHEL4-AS/root/ |
Copy Red Hat Enterprise Linux from the client system to the server using
rsync. For example:
rsync -a -e ssh installed-system.example.com:/ /diskless/i386/RHEL4-AS/root/ |
The length of this operation depends on the network connection
speed as well as the size of the file system on the installed system.
Depending on these factors, this operation may take a while.
Start the tftp server as discussed in Section 4.1 Start the tftp Server.
Configure the DHCP server as discussed in Section 4.2 Configuring the DHCP Server.
Finish creating the diskless environment as discussed in Section 4.4 Finish Configuring the Diskless Environment.
Configure the diskless clients as discussed in Section 4.5 Adding Hosts.
Configure each diskless client to boot via PXE and boot them.
On the DHCP server, verify that the tftp-server
package is installed with the command rpm -q
tftp-server. If it is not installed, install it via Red Hat Network or
the Red Hat Enterprise Linux CD-ROMs.
For more information on installing RPM packages,
refer to Part III Package Management.
tftp is an xinetd-based service; start it with the
following commands:
/sbin/chkconfig --level 345 xinetd on
/sbin/chkconfig --level 345 tftp on |
These commands configure the tftp and
xinetd services to immediately turn on and also
configure them to start at boot time in runlevels 3, 4, and 5.
