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/
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This directory is referred to as the diskless directory.
-
Create a subdirectory of this directory named root/:
mkdir -p /diskless/i386/RHEL4-AS/root/
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-
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/
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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
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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.
