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NOTE: CentOS Enterprise Linux is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux.
After the setup of basic cluster hardware, proceed with
installation of Red Hat Enterprise Linux on each node and ensure
that all systems recognize the connected devices. Follow these
steps:
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Install Red Hat Enterprise Linux on all cluster nodes. Refer to
Red Hat Enterprise Linux Installation
Guide for instructions.
In addition, when installing Red Hat Enterprise Linux, it is
strongly recommended to do the
following:
-
Gather the IP addresses for the nodes and for the bonded
Ethernet ports, before installing Red Hat Enterprise Linux. Note
that the IP addresses for the bonded Ethernet ports can be private
IP addresses, (for example, 10.x.x.x).
-
Do not place local file systems (such as /, /etc, /tmp, and /var) on shared
disks or on the same SCSI bus as shared disks. This helps prevent
the other cluster nodes from accidentally mounting these file
systems, and also reserves the limited number of SCSI
identification numbers on a bus for cluster disks.
-
Place /tmp and /var on different file systems. This may improve
node performance.
-
When a node boots, be sure that the node detects the disk
devices in the same order in which they were detected during the
Red Hat Enterprise Linux installation. If the devices are not
detected in the same order, the node may not boot.
-
When using certain RAID storage configured with Logical Unit
Numbers (LUNs) greater than
zero, it may be necessary to enable LUN support by adding the
following to /etc/modprobe.conf:
options scsi_mod max_scsi_luns=255
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-
Reboot the nodes.
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When using a terminal server, configure Red Hat Enterprise Linux
to send console messages to the console port.
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Edit the /etc/hosts file on each
cluster node and include the IP addresses used in the cluster or
ensure that the addresses are in DNS. Refer to Section 2.4.1
Editing the /etc/hosts File
for more information about performing this task.
-
Decrease the alternate kernel boot timeout limit to reduce boot
time for nodes. Refer to Section 2.4.2
Decreasing the Kernel Boot Timeout Limit for more
information about performing this task.
-
Ensure that no login (or getty)
programs are associated with the serial ports that are being used
for the remote power switch connection (if applicable). To perform
this task, edit the /etc/inittab file and
use a hash symbol (#) to comment out
the entries that correspond to the serial ports used for the remote
power switch. Then, invoke the init q
command.
-
Verify that all systems detect all the installed hardware:
-
Verify that the nodes can communicate over all the network
interfaces by using the ping command to
send test packets from one node to another.
-
If intending to configure Samba services, verify that the
required RPM packages for Samba services are installed.
The /etc/hosts file contains the IP
address-to-hostname translation table. The /etc/hosts file on each node must contain entries
for IP addresses and associated hostnames for all cluster
nodes.
As an alternative to the /etc/hosts
file, naming services such as DNS or NIS can be used to define the
host names used by a cluster. However, to limit the number of
dependencies and optimize availability, it is strongly recommended
to use the /etc/hosts file to define IP
addresses for cluster network interfaces.
The following is an example of an /etc/hosts file on a node of a cluster that does
not use DNS-assigned hostnames:
127.0.0.1 localhost.localdomain localhost
192.168.1.81 node1.example.com node1
193.186.1.82 node2.example.com node2
193.186.1.83 node3.example.com node3
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The previous example shows the IP addresses and hostnames for
three nodes (node1, node2, and node3),
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Important |
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Do not assign the node hostname to the
localhost (127.0.0.1) address, as this causes issues with the CMAN
cluster management system.
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Verify correct formatting of the local host entry in the
/etc/hosts file to ensure that it does
not include non-local systems in the entry for the local host. An
example of an incorrect local host entry that includes a non-local
system (server1) is shown next:
127.0.0.1 localhost.localdomain localhost server1
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An Ethernet connection may not operate properly if the format of
the /etc/hosts file is not correct. Check
the /etc/hosts file and correct the file
format by removing non-local systems from the local host entry, if
necessary.
Note that each network adapter must be configured with the
appropriate IP address and netmask.
The following example shows a portion of the output from the
/sbin/ip addr list command on a cluster
node:
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1356 qdisc pfifo_fast qlen 1000
link/ether 00:05:5d:9a:d8:91 brd ff:ff:ff:ff:ff:ff
inet 10.11.4.31/22 brd 10.11.7.255 scope global eth0
inet6 fe80::205:5dff:fe9a:d891/64 scope link
valid_lft forever preferred_lft forever
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You may also add the IP addresses for the cluster nodes to your
DNS server. Refer to the Red Hat Enterprise
Linux System Administration Guide for information on
configuring DNS, or consult your network administrator.
It is possible to reduce the boot time for a node by decreasing
the kernel boot timeout limit. During the Red Hat Enterprise Linux
boot sequence, the boot loader allows for specifying an alternate
kernel to boot. The default timeout limit for specifying a kernel
is ten seconds.
To modify the kernel boot timeout limit for a node, edit the
appropriate files as follows:
When using the GRUB boot loader, the timeout parameter in
/boot/grub/grub.conf should be modified
to specify the appropriate number of seconds for the timeout parameter. To set this interval to
3 seconds, edit the parameter to the following:
When using the LILO or ELILO boot loaders, edit the /etc/lilo.conf file (on x86 systems) or the
elilo.conf file (on Itanium systems) and
specify the desired value (in tenths of a second) for the
timeout parameter. The following
example sets the timeout limit to three seconds:
To apply any changes made to the /etc/lilo.conf file, invoke the /sbin/lilo command.
On an Itanium system, to apply any changes made to the
/boot/efi/efi/redhat/elilo.conf file,
invoke the /sbin/elilo command.
Use the dmesg command to display the
console startup messages. Refer to the dmesg(8)
man page for more information.
The following example of output from the dmesg command shows that two external SCSI buses and
nine disks were detected on the node. (Lines with backslashes
display as one line on most screens):
May 22 14:02:10 storage3 kernel: scsi0 : Adaptec AHA274x/284x/294x \
(EISA/VLB/PCI-Fast SCSI) 5.1.28/3.2.4
May 22 14:02:10 storage3 kernel:
May 22 14:02:10 storage3 kernel: scsi1 : Adaptec AHA274x/284x/294x \
(EISA/VLB/PCI-Fast SCSI) 5.1.28/3.2.4
May 22 14:02:10 storage3 kernel:
May 22 14:02:10 storage3 kernel: scsi : 2 hosts.
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST39236LW Rev: 0004
May 22 14:02:11 storage3 kernel: Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdb at scsi1, channel 0, id 0, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdc at scsi1, channel 0, id 1, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdd at scsi1, channel 0, id 2, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sde at scsi1, channel 0, id 3, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdf at scsi1, channel 0, id 8, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdg at scsi1, channel 0, id 9, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdh at scsi1, channel 0, id 10, lun 0
May 22 14:02:11 storage3 kernel: Vendor: SEAGATE Model: ST318203LC Rev: 0001
May 22 14:02:11 storage3 kernel: Detected scsi disk sdi at scsi1, channel 0, id 11, lun 0
May 22 14:02:11 storage3 kernel: Vendor: Dell Model: 8 BAY U2W CU Rev: 0205
May 22 14:02:11 storage3 kernel: Type: Processor \
ANSI SCSI revision: 03
May 22 14:02:11 storage3 kernel: scsi1 : channel 0 target 15 lun 1 request sense \
failed, performing reset.
May 22 14:02:11 storage3 kernel: SCSI bus is being reset for host 1 channel 0.
May 22 14:02:11 storage3 kernel: scsi : detected 9 SCSI disks total.
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The following example of the dmesg
command output shows that a quad Ethernet card was detected on the
node:
May 22 14:02:11 storage3 kernel: 3c59x.c:v0.99H 11/17/98 Donald Becker
May 22 14:02:11 storage3 kernel: tulip.c:v0.91g-ppc 7/16/99
May 22 14:02:11 storage3 kernel: eth0: Digital DS21140 Tulip rev 34 at 0x9800, \
00:00:BC:11:76:93, IRQ 5.
May 22 14:02:12 storage3 kernel: eth1: Digital DS21140 Tulip rev 34 at 0x9400, \
00:00:BC:11:76:92, IRQ 9.
May 22 14:02:12 storage3 kernel: eth2: Digital DS21140 Tulip rev 34 at 0x9000, \
00:00:BC:11:76:91, IRQ 11.
May 22 14:02:12 storage3 kernel: eth3: Digital DS21140 Tulip rev 34 at 0x8800, \
00:00:BC:11:76:90, IRQ 10.
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To be sure that the installed devices (such as network
interfaces), are configured in the kernel, use the cat /proc/devices command on each node. For
example:
Character devices:
1 mem
4 /dev/vc/0
4 tty
4 ttyS
5 /dev/tty
5 /dev/console
5 /dev/ptmx
6 lp
7 vcs
10 misc
13 input
14 sound
29 fb
89 i2c
116 alsa
128 ptm
136 pts
171 ieee1394
180 usb
216 rfcomm
226 drm
254 pcmcia
Block devices:
1 ramdisk
2 fd
3 ide0
8 sd
9 md
65 sd
66 sd
67 sd
68 sd
69 sd
70 sd
71 sd
128 sd
129 sd
130 sd
131 sd
132 sd
133 sd
134 sd
135 sd
253 device-mapper
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The previous example shows:
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