Build Your Own Oracle RAC 10g Release 2 Cluster on Linux and FireWire (Continued)

For development and testing only; production deployments will not be supported!

Perform the following configuration procedures on all nodes in the cluster!

The kernel parameters discussed in this section will need to be defined on every node within the cluster every time the machine is booted. This section provides very detailed information about setting those kernel parameters required for Oracle. Instructions for placing them in a startup script (/etc/sysctl.conf) are included in Section 14 ("All Startup Commands for Each RAC Node").

Overview

This section focuses on configuring both Linux servers - getting each one prepared for the Oracle RAC 10g installation. This includes verifying enough swap space, setting shared memory and semaphores, setting the maximum amount of file handles, setting the IP local port range, setting shell limits for the oracle user, activating all kernel parameters for the system, and finally how to verify the correct date and time for each node in the cluster.

Throughout this section you will notice that there are several different ways to configure (set) these parameters. For the purpose of this article, I will be making all changes permanent (through reboots) by placing all commands in the /etc/sysctl.conf file.

Swap Space Considerations

• Installing Oracle10g Release 2 requires a minimum of 512MB of memory. (Note: An inadequate amount of swap during the installation will cause the Oracle Universal Installer to either "hang" or "die")
• To check the amount of memory / swap you have allocated, type either:

  # cat /proc/meminfo | grep MemTotal
  MemTotal: 1034352 kB
  

• If you have less than 512MB of memory (between your RAM and SWAP), you can add temporary swap space by creating a temporary swap file. This way you do not have to use a raw device or even more drastic, rebuild your system.

  As root, make a file that will act as additional swap space, let's say about 300MB:
  
  # dd if=/dev/zero of=tempswap bs=1k count=300000

  Now we should change the file permissions:
  
  # chmod 600 tempswap

  Finally we format the "partition" as swap and add it to the swap space:
  
  # mke2fs tempswap
  # mkswap tempswap
  # swapon tempswap
  

Setting Shared Memory

Shared memory allows processes to access common structures and data by placing them in a shared memory segment. This is the fastest form of inter-process communications (IPC) available, mainly due to the fact that no kernel involvement occurs when data is being passed between the processes. Data does not need to be copied between processes.

Oracle makes use of shared memory for its Shared Global Area (SGA) which is an area of memory that is shared by all Oracle backup and foreground processes. Adequate sizing of the SGA is critical to Oracle performance because it is responsible for holding the database buffer cache, shared SQL, access paths, and so much more.

To determine all shared memory limits, use the following:

# ipcs -lm
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 32768
max total shared memory (kbytes) = 8388608
min seg size (bytes) = 1

Setting SHMMAX

The SHMMAX parameters defines the maximum size (in bytes) for a shared memory segment. The Oracle SGA is comprised of shared memory and it is possible that incorrectly setting SHMMAX could limit the size of the SGA. When setting SHMMAX, keep in mind that the size of the SGA should fit within one shared memory segment. An inadequate SHMMAX setting could result in the following:

ORA-27123: unable to attach to shared memory segment

You can determine the value of SHMMAX by performing the following:

# cat /proc/sys/kernel/shmmax
33554432

The default value for SHMMAX is 32MB. This size is often too small to configure the Oracle SGA. I generally set the SHMMAX parameter to 2GB using the following methods:

• You can alter the default setting for SHMMAX without rebooting the machine by making the changes directly to the /proc file system (/proc/sys/kernel/shmmax) by using the following command:

  # sysctl -w kernel.shmmax=2147483648
              

• You should then make this change permanent by inserting the kernel parameter in the /etc/sysctl.conf startup file:

  # echo "kernel.shmmax=2147483648" >> /etc/sysctl.conf
              

Setting SHMMNI

We now look at the SHMMNI parameters. This kernel parameter is used to set the maximum number of shared memory segments system wide. The default value for this parameter is 4096.

You can determine the value of SHMMNI by performing the following:

# cat /proc/sys/kernel/shmmni
4096

The default setting for SHMMNI should be adequate for your Oracle RAC 10g Release 2 installation.

Setting SHMALL

Finally, we look at the SHMALL shared memory kernel parameter. This parameter controls the total amount of shared memory (in pages) that can be used at one time on the system. In short, the value of this parameter should always be at least:

ceil(SHMMAX/PAGE_SIZE)

The default size of SHMALL is 2097152 and can be queried using the following command:

# cat /proc/sys/kernel/shmall
2097152

The default setting for SHMALL should be adequate for our Oracle RAC 10g Release 2 installation.

(Note: The page size in Red Hat Linux on the i386 platform is 4,096 bytes. You can, however, use bigpages which supports the configuration of larger memory page sizes.)

Setting Semaphores

Now that you have configured our shared memory settings, it is time to configure your semaphores. The best way to describe a "semaphore" is as a counter that is used to provide synchronization between processes (or threads within a process) for shared resources like shared memory. Semaphore sets are supported in UNIX System V where each one is a counting semaphore. When an application requests semaphores, it does so using "sets."

To determine all semaphore limits, use the following:

# ipcs -ls
------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

# cat /proc/sys/kernel/sem
250 32000 32 128

Setting SEMMSL

The SEMMSL kernel parameter is used to control the maximum number of semaphores per semaphore set.

Oracle recommends setting SEMMSL to the largest PROCESS instance parameter setting in the init.ora file for all databases on the Linux system plus 10. Also, Oracle recommends setting the SEMMSL to a value of no less than 100.

Setting SEMMNI

The SEMMNI kernel parameter is used to control the maximum number of semaphore sets in the entire Linux system. Oracle recommends setting the SEMMNI to a value of no less than 100.

Setting SEMMNS

The SEMMNS kernel parameter is used to control the maximum number of semaphores (not semaphore sets) in the entire Linux system.

Oracle recommends setting the SEMMNS to the sum of the PROCESSES instance parameter setting for each database on the system, adding the largest PROCESSES twice, and then finally adding 10 for each Oracle database on the system.

Use the following calculation to determine the maximum number of semaphores that can be allocated on a Linux system. It will be the lesser of:

SEMMNS -or- (SEMMSL * SEMMNI)

Setting SEMOPM

The SEMOPM kernel parameter is used to control the number of semaphore operations that can be performed per semop system call.

The semop system call (function) provides the ability to do operations for multiple semaphores with one semop system call. A semaphore set can have the maximum number of SEMMSL semaphores per semaphore set and is therefore recommended to set SEMOPM equal to SEMMSL.

Oracle recommends setting the SEMOPM to a value of no less than 100.

Setting Semaphore Kernel Parameters

Finally, we see how to set all semaphore parameters using several methods. In the following, the only parameter I care about changing (raising) is SEMOPM. All other default settings should be sufficient for our example installation.

• You can alter the default setting for all semaphore settings without rebooting the machine by making the changes directly to the /proc file system (/proc/sys/kernel/sem) by using the following command:

  # sysctl -w kernel.sem="250 32000 100 128"

• You should then make this change permanent by inserting the kernel parameter in the /etc/sysctl.conf startup file:

  # echo "kernel.sem=250 32000 100 128" >> /etc/sysctl.conf
              

Setting File Handles

When configuring our Red Hat Linux server, it is critical to ensure that the maximum number of file handles is sufficiently large. The setting for file handles denotes the number of open files that you can have on the Linux system.

Use the following command to determine the maximum number of file handles for the entire system:

# cat /proc/sys/fs/file-max
102563

• You can alter the default setting for the maximum number of file handles without rebooting the machine by making the changes directly to the /proc file system (/proc/sys/fs/file-max) using the following:

  # sysctl -w fs.file-max=65536
            

• You should then make this change permanent by inserting the kernel parameter in the /etc/sysctl.conf startup file:

  # echo "fs.file-max=65536" >> /etc/sysctl.conf
            

# cat /proc/sys/fs/file-nr
825 0 65536

(Note: If you need to increase the value in /proc/sys/fs/file-max, then make sure that the ulimit is set properly. Usually for 2.4.20 it is set to unlimited. Verify the ulimit setting my issuing the ulimit command:

# ulimit
unlimited

Setting IP Local Port Range

Configure the system to allow a local port range of 1024 through 65000.

Use the following command to determine the value of ip_local_port_range:

# cat /proc/sys/net/ipv4/ip_local_port_range
32768 61000

• You can alter the default setting for the local port range without rebooting the machine by making the changes directly to the /proc file system (/proc/sys/net/ipv4/ip_local_port_range) by using the following command:

  # sysctl -w net.ipv4.ip_local_port_range="1024 65000"

• You should then make this change permanent by inserting the kernel parameter in the /etc/sysctl.conf startup file:

  # echo "net.ipv4.ip_local_port_range = 1024 65000" >> /etc/sysctl.conf

Setting Shell Limits for the oracle User

cat >> /etc/security/limits.conf <<EOF
oracle soft nproc 2047
oracle hard nproc 16384
oracle soft nofile 1024
oracle hard nofile 65536
EOF

cat >> /etc/pam.d/login <<EOF
session required /lib/security/pam_limits.so
EOF

• For the Bourne, Bash, or Korn shell, add the following lines to the /etc/profile file by running the following command:

  cat >> /etc/profile <<EOF
  if [ \$USER = "oracle" ]; then 
   if [ \$SHELL = "/bin/ksh" ]; then
   ulimit -p 16384
   ulimit -n 65536
   else
   ulimit -u 16384 -n 65536
   fi
   umask 022
  fi
  EOF

• For the C shell (csh or tcsh), add the following lines to the /etc/csh.login file by running the following command:

  cat >> /etc/csh.login <<EOF
  if ( \$USER == "oracle" ) then
   limit maxproc 16384
   limit descriptors 65536
  endif
  EOF

Activating All Kernel Parameters for the System

# sysctl -p
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.core.rmem_default = 262144
net.core.wmem_default = 262144
net.core.rmem_max = 262144
net.core.wmem_max = 262144
kernel.shmmax = 2147483648
kernel.sem = 250 32000 100 128
fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000

Setting the Correct Date and Time on All Cluster Nodes

Error while copying directory 
 /u01/app/oracle/product/crs with exclude file list 'null' to nodes 'linux2'.
[PRKC-1002 : All the submitted commands did not execute successfully]
---------------------------------------------
linux2:
 /bin/tar: ./bin/lsnodes: time stamp 2006-09-13 09:21:34 is 735 s in the future
 /bin/tar: ./bin/olsnodes: time stamp 2006-09-13 09:21:34 is 735 s in the future
 ...(more errors on this node)

# date -s "9/13/2006 23:00:00"

# date -s "9/13/2006 23:00:20"

Perform the following configuration procedures on all nodes in the cluster!

Oracle9i Release 1 (9.0.1) and Oracle9i Release 2 ( 9.2.0.1) used a userspace watchdog daemon called watchdogd to monitor the health of the cluster and to restart a RAC node in case of a failure. Starting with Oracle9i Release 2 (9.2.0.2) (and still available in Oracle 10g Release 2), the watchdog daemon has been deprecated by a Linux kernel module named hangcheck-timer which addresses availability and reliability problems much better. The hang-check timer is loaded into the Linux kernel and checks if the system hangs. It will set a timer and check the timer after a certain amount of time. There is a configurable threshold to hang-check that, if exceeded will reboot the machine. Although the hangcheck-timer module is not required for Oracle Clusterware (Cluster Manager) operation, it is highly recommended by Oracle.

The hangcheck-timer.ko Module

The hangcheck-timer module uses a kernel-based timer that periodically checks the system task scheduler to catch delays in order to determine the health of the system. If the system hangs or pauses, the timer resets the node. The hangcheck-timer module uses the Time Stamp Counter (TSC) CPU register, which is incremented at each clock signal. The TCS offers much more accurate time measurements because this register is updated by the hardware automatically.

Much more information about the hangcheck-timer project can be found here.

Installing the hangcheck-timer.ko Module

The hangcheck-timer was normally shipped only by Oracle, however, this module is now included with Red Hat Linux AS starting with kernel versions 2.4.9-e.12 and higher. The hangcheck-timer should already be included. Use the following to ensure that you have the module included:

# find /lib/modules -name "hangcheck-timer.ko"
/lib/modules/2.6.9-22.EL/kernel/drivers/char/hangcheck-timer.ko

Configuring and Loading the hangcheck-timer Module

There are two key parameters to the hangcheck-timer module:

• hangcheck-tick: This parameter defines the period of time between checks of system health. The default value is 60 seconds; Oracle recommends setting it to 30 seconds.
• hangcheck-margin: This parameter defines the maximum hang delay that should be tolerated before hangcheck-timer resets the RAC node. It defines the margin of error in seconds. The default value is 180 seconds; Oracle recommends setting it to 180 seconds.

system hang time > (hangcheck_tick + hangcheck_margin)

Each time the hangcheck-timer kernel module is loaded (manually or by Oracle), it needs to know what value to use for each of the two parameters we just discussed: (hangcheck-tick and hangcheck-margin). These values need to be available after each reboot of the Linux server. To do that, make an entry with the correct values to the /etc/modprobe.conf file as follows:

# su -
# echo "options hangcheck-timer hangcheck_tick=30 hangcheck_margin=180" >> /etc/modprobe.conf
      

Manually Loading the Hangcheck Kernel Module for Testing

Oracle is responsible for loading the hangcheck-timer kernel module when required. For that reason, it is not required to perform a modprobe or insmod of the hangcheck-timer kernel module in any of the startup files (i.e. /etc/rc.local).

It is only out of pure habit that I continue to include a modprobe of the hangcheck-timer kernel module in the /etc/rc.local file. Someday I will get over it, but realize that it does not hurt to include a modprobe of the hangcheck-timer kernel module during startup.

So to keep myself sane and able to sleep at night, I always configure the loading of the hangcheck-timer kernel module on each startup as follows:

# echo "/sbin/modprobe hangcheck-timer" >> /etc/rc.local
      

(Note: You don't have to manually load the hangcheck-timer kernel module using modprobe or insmod after each reboot. The hangcheck-timer module will be loaded by Oracle automatically when needed.)

Now, to test the hangcheck-timer kernel module to verify it is picking up the correct parameters we defined in the /etc/modprobe.conf file, use the modprobe command. Although you could load the hangcheck-timer kernel module by passing it the appropriate parameters (e.g. insmod hangcheck-timer hangcheck_tick=30 hangcheck_margin=180), we want to verify that it is picking up the options we set in the /etc/modprobe.conf file.

To manually load the hangcheck-timer kernel module and verify it is using the correct values defined in the /etc/modprobe.conf file, run the following command:

# su -
# modprobe hangcheck-timer
# grep Hangcheck /var/log/messages | tail -2
Dec 19 21:04:40 linux2 kernel: Hangcheck: starting hangcheck timer 0.5.0 (tick is 30 seconds, margin is 180 seconds)
      

Perform the following configuration procedures on all nodes in the cluster!

• Using the Secure Shell Method
• Using the Remote Shell Method

This section describes how to configure OpenSSH version 3.

To determine if SSH is installed and running, enter the following command:

# pgrep sshd
2808
4440
4442
6067
6069

If SSH is running, then the response to this command is a list of process ID number(s). Please run this command on all nodes in the cluster to verify the SSH daemons are installed and running!

To find out more about SSH, refer to the man page:

# man ssh

Creating RSA and DSA Keys on Each Node

The first step in configuring SSH is to create RSA and DSA key pairs on each node in the cluster. The command to do this will create a public and private key for both RSA and DSA (for a total of four keys per node). The content of the RSA and DSA public keys will then need to be copied into an authorized key file which is then distributed to all nodes in the cluster.

Use the following steps to create the RSA and DSA key pairs. Please note that these steps will need to be completed on all nodes in the cluster:

1. Logon as the "oracle" UNIX user account.

   # su - oracle

2. If necessary, create the .ssh directory in the "oracle" user's home directory and set the correct permissions on it:

   $ mkdir -p ~/.ssh
   $ chmod 700 ~/.ssh

3. Enter the following command to generate an RSA key pair (public and private key) for version 3 of the SSH protocol:

   $ /usr/bin/ssh-keygen -t rsa

   At the prompts:
   • Accept the default location for the key files.
   • Enter and confirm a pass phrase. This should be different from the "oracle" UNIX user account password however it is not a requirement.

   This command will write the public key to the ~/.ssh/id_rsa.pub file and the private key to the ~/.ssh/id_rsa file. Note that you should never distribute the private key to anyone!

4. Enter the following command to generate a DSA key pair (public and private key) for version 3 of the SSH protocol:

   $ /usr/bin/ssh-keygen -t dsa

   At the prompts:
   • Accept the default location for the key files.
   • Enter and confirm a pass phrase. This should be different from the "oracle" UNIX user account password however it is not a requirement.

   This command will write the public key to the ~/.ssh/id_dsa.pub file and the private key to the ~/.ssh/id_dsa file. Note that you should never distribute the private key to anyone!

5. Repeat the above steps for each node in the cluster.

Now that each node contains a public and private key for both RSA and DSA, you will need to create an authorized key file on one of the nodes. An authorized key file is nothing more than a single file that contains a copy of everyone's (every node's) RSA and DSA public key. Once the authorized key file contains all of the public keys, it is then distributed to all other nodes in the cluster.

Complete the following steps on one of the nodes in the cluster to create and then distribute the authorized key file. For the purpose of this article, I am using linux1:

1. First, determine if an authorized key file already exists on the node (~/.ssh/authorized_keys). In most cases this will not exist since this article assumes you are working with a new install. If the file doesn't exist, create it now:

   $ touch ~/.ssh/authorized_keys
   $ cd ~/.ssh
   $ ls -l *.pub
   -rw-r--r-- 1 oracle dba 603 Aug 31 23:40 id_dsa.pub
   -rw-r--r-- 1 oracle dba 223 Aug 31 23:36 id_rsa.pub

   The listing above should show the id_rsa.pub and id_dsa.pub public keys created in the previous section.

2. In this step, use SSH to copy the content of the ~/.ssh/id_rsa.pub and ~/.ssh/id_dsa.pub public key from each node in the cluster to the authorized key file just created (~/.ssh/authorized_keys). Again, this will be done from linux1. You will be prompted for the "oracle" UNIX user account password for each node accessed. Notice that when using SSH to access the node you are on (linux1), the first time prompts for the "oracle" UNIX user account password. The second attempt at accessing this node will prompt for the pass phrase used to unlock the private key. For any of the remaining nodes, it will always ask for the "oracle" UNIX user account password.

   The following example is being run from linux1 and assumes a two-node cluster, with nodes linux1 and linux2:

   $ ssh linux1 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
   The authenticity of host 'linux1 (192.168.1.100)' can't be established.
   RSA key fingerprint is 61:8a:f9:9e:28:a2:b7:d3:70:8d:dc:76:ca:d9:23:43.
   Are you sure you want to continue connecting (yes/no)? yes
   Warning: Permanently added 'linux1,192.168.1.100' (RSA) to the list of known hosts.
   oracle@linux1's password: xxxxx
   $ ssh linux1 cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
   Enter passphrase for key '/u01/app/oracle/.ssh/id_rsa': xxxxx
   $ ssh linux2 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
   The authenticity of host 'linux2 (192.168.1.101)' can't be established.
   RSA key fingerprint is 84:2b:bd:eb:31:2c:23:36:55:c2:ee:54:d2:23:6a:e4.
   Are you sure you want to continue connecting (yes/no)? yes
   Warning: Permanently added 'linux2,192.168.1.101' (RSA) to the list of known hosts.
   oracle@linux2's password: xxxxx
   $ ssh linux2 cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
   oracle@linux2's password: xxxxx

   Note: The first time you use SSH to connect to a node from a particular system, you may see a message similar to the following:

   The authenticity of host 'linux1 (192.168.1.100)' can't be established.
   RSA key fingerprint is 61:8a:f9:9e:28:a2:b7:d3:70:8d:dc:76:ca:d9:23:43.
   Are you sure you want to continue connecting (yes/no)? yes

   Enter yes at the prompt to continue. You should not see this message again when you connect from this system to the same node.

3. At this point, we have the content of the RSA and DSA public keys from every node in the cluster in the authorized key file (~/.ssh/authorized_keys) on linux1. We now need to copy it to the remaining nodes in the cluster. In our two-node cluster example, the only remaining node is linux2. Use the scp command to copy the authorized key file to all remaining nodes in the cluster:

   $ scp ~/.ssh/authorized_keys linux2:.ssh/authorized_keys
   oracle@linux2's password: xxxxx
   authorized_keys 100% 1652 1.6KB/s 00:00

4. Change the permission of the authorized key file for each node in the cluster by logging into the node and running the following:

   $ chmod 600 ~/.ssh/authorized_keys

5. At this point, if you use ssh to log in to or run a command on another node, you are prompted for the pass phrase that you specified when you created the DSA key. For example, test the following from linux1:

   $ ssh linux1 hostname
   Enter passphrase for key '/u01/app/oracle/.ssh/id_rsa': xxxxx
   linux1
   $ ssh linux2 hostname
   Enter passphrase for key '/u01/app/oracle/.ssh/id_rsa': xxxxx
   linux2

   Note: If you see any other messages or text, apart from the host name, then the Oracle installation can fail. Make any changes required to ensure that only the host name is displayed when you enter these commands. You should ensure that any part of a login script(s) that generate any output, or ask any questions, are modified so that they act only when the shell is an interactive shell.

Enabling SSH User Equivalency for the Current Shell Session

When running the OUI, it will need to run the secure shell tool commands (ssh and scp) without being prompted for a pass phrase. Even though SSH is configured on all nodes in the cluster, using the secure shell tool commands will still prompt for a pass phrase. Before running the OUI, you need to enable user equivalence for the terminal session you plan to run the OUI from. For the purpose of this article, all Oracle installations will be performed from linux1.

User equivalence will need to be enabled on any new terminal shell session before attempting to run the OUI. If you log out and log back in to the node you will be performing the Oracle installation from, you must enable user equivalence for the terminal shell session as this is not done by default.

To enable user equivalence for the current terminal shell session, perform the following steps:

1. Logon to the node where you want to run the OUI from (linux1) as the "oracle" UNIX user account.

   # su - oracle

2. Enter the following commands:

   $ exec /usr/bin/ssh-agent $SHELL
   $ /usr/bin/ssh-add
   Enter passphrase for /u01/app/oracle/.ssh/id_rsa: xxxxx
   Identity added: /u01/app/oracle/.ssh/id_rsa (/u01/app/oracle/.ssh/id_rsa)
   Identity added: /u01/app/oracle/.ssh/id_dsa (/u01/app/oracle/.ssh/id_dsa)

   At the prompts, enter the pass phrase for each key that you generated.

3. If SSH is configured correctly, you will be able to use the ssh and scp commands without being prompted for a password or pass phrase from this terminal session:

   $ ssh linux1 "date;hostname"
   Wed Sep 13 17:35:30 EDT 2006
   linux1
   $ ssh linux2 "date;hostname"
   Wed Sep 13 17:36:14 EDT 2006
   linux2

   Note: The commands above should display the date set on each node along with its hostname. If any of the nodes prompt for a password or pass phrase then verify that the ~/.ssh/authorized_keys file on that node contains the correct public keys. Also, if you see any other messages or text, apart from the date and hostname, then the Oracle installation can fail. Make any changes required to ensure that only the date is displayed when you enter these commands. You should ensure that any part of a login script(s) that generate any output, or ask any questions, are modified so that they act only when the shell is an interactive shell.

4. The Oracle Universal Installer is a GUI interface and requires the use of an X Server. From the terminal session enabled for user equivalence (the node you will be performing the Oracle installations from), set the environment variable DISPLAY to a valid X Windows display:

   Bourne, Korn, and Bash shells:

   $ DISPLAY=<Any X-Windows Host>:0
   $ export DISPLAY

   C shell:

   $ setenv DISPLAY <Any X-Windows Host>:0

   After setting the DISPLAY variable to a valid X Windows display, you should perform another test of the current terminal session to ensure that X11 forwarding is not enabled:

   $ ssh linux1 hostname
   linux1
   $ ssh linux2 hostname
   linux2

   Note: If you are using a remote client to connect to the node performing the installation, and you see a message similar to: "Warning: No xauth data; using fake authentication data for X11 forwarding." then this means that your authorized keys file is configured correctly; however, your SSH configuration has X11 forwarding enabled. For example:

   $ export DISPLAY=melody:0
   $ ssh linux2 hostname
   Warning: No xauth data; using fake authentication data for X11 forwarding.
   linux2

   Note that having X11 Forwarding enabled will cause the Oracle installation to fail. To correct this problem, create a user-level SSH client configuration file for the "oracle" UNIX user account that disables X11 Forwarding:
   • Using a text editor, edit or create the file ~/.ssh/config
   • Make sure that the ForwardX11 attribute is set to no. For example, insert the following into the ~/.ssh/config file:

     Host *
      ForwardX11 no

   • You must run the Oracle Universal Installer from this terminal session or remember to repeat the steps to enable user equivalence (steps 2, 3, and 4 from this section) before you start the Oracle Universal Installer from a different terminal session.

Remove any stty Commands

When installing the Oracle software, any hidden files on the system (i.e. .bashrc, .cshrc, .profile) will cause the installation process to fail if they contain stty commands.

To avoid this problem, you must modify these files to suppress all output on STDERR as in the following examples:

• Bourne, Bash, or Korn shell:

  if [ -t 0 ]; then
   stty intr ^C
  fi

• C shell:

  test -t 0
  if ($status == 0) then
   stty intr ^C
  endif

Note: If there are hidden files that contain stty commands that are loaded by the remote shell, then OUI indicates an error and stops the installation.

The services provided by remote shell are disabled by default on most Linux systems. This section describes the tasks required for enabling and configuring user equivalence for use by the Oracle Universal Installer when commands should be run and files copied to the remote nodes in the cluster using the remote shell tools. The goal is to enable the Oracle Universal Installer to use rsh and rcp to run commands and copy files to a remote node without being prompted for a password. Please note that using the remote shell method for configuring user equivalence is not secure.

The rsh daemon validates users using the /etc/hosts.equiv file or the .rhosts file found in the user's (oracle's) home directory.

First, let's make sure that we have the rsh RPMs installed on each node in the RAC cluster:

# rpm -q rsh rsh-server
rsh-0.17-25.3
rsh-server-0.17-25.3

From the above, we can see that we have the rsh and rsh-server installed. Were rsh not installed, we would run the following command from the CD where the RPM is located:

# su -
# rpm -ivh rsh-0.17-25.3.i386.rpm rsh-server-0.17-25.3.i386.rpm

To enable the "rsh" and "rlogin" services, the "disable" attribute in the /etc/xinetd.d/rsh file must be set to "no" and xinetd must be reloaded. This can be done by running the following commands on all nodes in the cluster:

# su -
# chkconfig rsh on
# chkconfig rlogin on
# service xinetd reload
Reloading configuration: [ OK ]

To allow the "oracle" UNIX user account to be trusted among the RAC nodes, create the /etc/hosts.equiv file on all nodes in the cluster:

# su -
# touch /etc/hosts.equiv
# chmod 600 /etc/hosts.equiv
# chown root.root /etc/hosts.equiv

Now add all RAC nodes to the /etc/hosts.equiv file similar to the following example for all nodes in the cluster:

# cat /etc/hosts.equiv
+linux1 oracle
+linux2 oracle
+linux1-priv oracle
+linux2-priv oracle

Note: In the above example, the second field permits only the oracle user account to run rsh commands on the specified nodes. For security reasons, the /etc/hosts.equiv file should be owned by root and the permissions should be set to 600. In fact, some systems will only honor the content of this file if the owner of this file is root and the permissions are set to 600.

Before attempting to test your rsh command, ensure that you are using the correct version of rsh. By default, Red Hat Linux puts /usr/kerberos/sbin at the head of the $PATH variable. This will cause the Kerberos version of rsh to be executed.

I will typically rename the Kerberos version of rsh so that the normal rsh command will be used. Use the following:

# su -
# which rsh
/usr/kerberos/bin/rsh
# mv /usr/kerberos/bin/rsh /usr/kerberos/bin/rsh.original
# mv /usr/kerberos/bin/rcp /usr/kerberos/bin/rcp.original
# mv /usr/kerberos/bin/rlogin /usr/kerberos/bin/rlogin.original
# which rsh
/usr/bin/rsh

You should now test your connections and run the rsh command from the node that will be performing the Oracle Clusterware and 10g RAC installation. I will be using the node linux1 to perform all installs so this is where I will run the following commands from:

# su - oracle
$ rsh linux1 ls -l /etc/hosts.equiv
-rw------- 1 root root 68 Sep 27 23:37 /etc/hosts.equiv
$ rsh linux1-priv ls -l /etc/hosts.equiv
-rw------- 1 root root 68 Sep 27 23:37 /etc/hosts.equiv
$ rsh linux2 ls -l /etc/hosts.equiv
-rw------- 1 root root 68 Sep 27 23:45 /etc/hosts.equiv
$ rsh linux2-priv ls -l /etc/hosts.equiv
-rw------- 1 root root 68 Sep 27 23:45 /etc/hosts.equiv

Unlike when using secure shell, no other actions or commands are needed to enable user equivalence using the remote shell. User equivalence will be enabled for the "oracle" UNIX user account after successfully logging in to a terminal session.

Verify that the following startup commands are included on all nodes in the cluster!

Up to this point, you have read in great detail about the parameters and resources that need to be configured on all nodes for the Oracle10g RAC configuration. This section will let you " take a deep breath" and recap those parameters, commands, and entries (in previous sections of this document) that need to happen on each node when the machine is booted.

For each of the startup files below, entries in gray should be included in each startup file.

/etc/modprobe.conf

(All parameters and values to be used by kernel modules.)

alias eth0 b44
alias eth1 tulip
alias snd-card-0 snd-intel8x0
options snd-card-0 index=0
alias usb-controller ehci-hcd
alias usb-controller1 uhci-hcd
options sbp2 exclusive_login=0
alias scsi_hostadapter sbp2
options hangcheck-timer hangcheck_tick=30 hangcheck_margin=180
      

/etc/sysctl.conf

(We wanted to adjust the default and maximum send buffer size as well as the default and maximum receive buffer size for the interconnect. This file also contains those parameters responsible for configuring shared memory, semaphores, file handles, and local IP range for use by the Oracle instance.)

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
# sysctl.conf(5) for more details.

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1

# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0

# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1

# Default setting in bytes of the socket receive buffer
net.core.rmem_default=262144

# Default setting in bytes of the socket send buffer
net.core.wmem_default=262144

# Maximum socket receive buffer size which may be set by using
# the SO_RCVBUF socket option
net.core.rmem_max=262144

# Maximum socket send buffer size which may be set by using
# the SO_SNDBUF socket option
net.core.wmem_max=262144
# +---------------------------------------------------------+
# | SHARED MEMORY |
# +---------------------------------------------------------+
kernel.shmmax=2147483648

# +---------------------------------------------------------+
# | SEMAPHORES |
# | ---------- |
# | |
# | SEMMSL_value SEMMNS_value SEMOPM_value SEMMNI_value |
# | |
# +---------------------------------------------------------+
kernel.sem=250 32000 100 128

# +---------------------------------------------------------+
# | FILE HANDLES |
# ----------------------------------------------------------+
fs.file-max=65536

# +---------------------------------------------------------+
# | LOCAL IP RANGE |
# ----------------------------------------------------------+
net.ipv4.ip_local_port_range=1024 65000
      

/etc/hosts

(All machine/IP entries for nodes in our RAC cluster.)

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
# Public Network - (eth0)
192.168.1.100 linux1
192.168.1.101 linux2
# Private Interconnect - (eth1)
192.168.2.100 linux1-priv
192.168.2.101 linux2-priv
# Public Virtual IP (VIP) addresses for - (eth0)
192.168.1.200 linux1-vip
192.168.1.201 linux2-vip
192.168.1.106 melody
192.168.1.102 alex
192.168.1.105 bartman

/etc/hosts.equiv

(The /etc/hosts.equiv file is only required when using the remote shell method to establish remote access and user equivalency. Allow logins to each node as the oracle user account without the need for a password when using the remote shell method for enabling user equivalency.)

+linux1 oracle
+linux2 oracle
+linux1-priv oracle
+linux2-priv oracle
      

/etc/rc.local

(Loading the hangcheck-timer kernel module.)

#!/bin/sh
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local

# +---------------------------------------------------------+
# | HANGCHECK TIMER |
# | (I do not believe this is required, but doesn't hurt) |
# ----------------------------------------------------------+

/sbin/modprobe hangcheck-timer
      

Perform the following checks on all nodes in the cluster!

When installing the Linux O/S (CentOS Enterprise Linux or RHEL4), you should verify that all required RPMs are installed. If you followed the instructions I used for installing Linux, you would have installed everything, in which case you will have all the required RPM packages. However, if you performed another installation type (i.e. Advanced Server), you may have some packages missing and will need to install them. All of the required RPMs are on the Linux CDs/ISOs.

Check Required RPMs

The following packages (or higher versions) must be installed:

make-3.80-5
glibc-2.3.4-2.9
glibc-devel-2.3.4-2.9
glibc-headers-2.3.4-2.9
glibc-kernheaders-2.4-9.1.87
cpp-3.4.3-22.1
compat-db-4.1.25-9
compat-gcc-32-3.2.3-47.3
compat-gcc-32-c++-3.2.3-47.3
compat-libstdc++-33-3.2.3-47.3
compat-libstdc++-296-2.96-132.7.2
openmotif-2.2.3-9.RHEL4.1
setarch-1.6-1

To query package information (gcc and glibc-devel for example), use the "rpm -q <PackageName> [, <PackageName>]" command as follows:

# rpm -q gcc glibc-devel
gcc-3.4.3-22.1
glibc-devel-2.3.4-2.9

# rpm -Uvh gcc-3.4.3-22.1.i386.rpm
      

If you made any changes to the O/S, reboot all nodes in the cluster before attempting to install any of the Oracle components!!!

# init 6
      

Most of the configuration procedures in this section should be performed on all nodes in the cluster! Creating the OCFS2 filesystem, however, should be executed on only one node in the cluster.

It is now time to install OCFS2. OCFS2 is a cluster filesystem that allows all nodes in a cluster to concurrently access a device via the standard filesystem interface. This allows for easy management of applications that need to run across a cluster.

OCFS Release 1 was released in 2002 to enable Oracle RAC users to run the clustered database without having to deal with RAW devices. The filesystem was designed to store database related files, such as data files, control files, redo logs, archive logs, etc. OCFS Release 2 (OCFS2), in contrast, has been designed as a general-purpose cluster filesystem. With it, one can store not only database related files on a shared disk, but also store Oracle binaries and configuration files (shared Oracle Home) making management of RAC even easier.

In this guide, you will be using the latest release of OCFS2 (OCFS2 Release 1.2.3-1 at the time of this writing) to store the two files that are required to be shared by the Oracle Clusterware software. Along with these two files, you will also be using this space to store the shared SPFILE for all Oracle RAC instances.

See this page for more information on OCFS2 (including Installation Notes) for Linux.

Download OCFS

First, download the latest OCFS2 distribution. The OCFS2 distribution comprises of two sets of RPMs; namely, the kernel module and the tools. The latest kernel module is available for download from http://oss.oracle.com/projects/ocfs2/files/ and the tools from http://oss.oracle.com/projects/ocfs2-tools/files/.

Download the appropriate RPMs starting with the latest OCFS2 kernel module (the driver). With CentOS 4.2 Enterprise Linux, I am using kernel release 2.6.9-22.EL. The appropriate OCFS2 kernel module was found in the latest release of OCFS2 at the time of this writing (OCFS2 Release 1.2.3-1). The available OCFS2 kernel modules for Linux kernel 2.6.9-22.EL are listed below. Always download the latest OCFS2 kernel module that matches the distribution, platform, kernel version and the kernel flavor (smp, hugemem, psmp, etc).

ocfs2-2.6.9-22.EL-1.2.3-1.i686.rpm - (for single processor)

or

ocfs2-2.6.9-22.ELsmp-1.2.3-1.i686.rpm - (for multiple processors)

or

ocfs2-2.6.9-22.ELhugemem-1.2.3-1.i686.rpm - (for hugemem)

For the tools, simply match the platform and distribution. You should download the OCFS2 tools as well as the OCFS2 console applications.

ocfs2-tools-1.2.1-1.i386.rpm - (OCFS2 tools)
ocfs2console-1.2.1-1.i386.rpm - (OCFS2 console)

The OCFS2 Console is optional but highly recommended. The ocfs2console application requires e2fsprogs, glib2 2.2.3 or later, vte 0.11.10 or later, pygtk2 (EL4) or python-gtk (SLES9) 1.99.16 or later, python 2.3 or later and ocfs2-tools.

If you were curious as to which OCFS2 driver release you need, use the OCFS2 release that matches your kernel version. To determine your kernel release:

$ uname -a
Linux linux1 2.6.9-22.EL #1 Sat Oct 8 17:48:27 CDT 2005 i686 i686 i386 GNU/Linux

Install OCFS2

I will be installing the OCFS2 files onto two single-processor machines. The installation process is simply a matter of running the following command on all nodes in the cluster as the root user account:

$ su -
# rpm -Uvh ocfs2-2.6.9-22.EL-1.2.3-1.i686.rpm \
 ocfs2console-1.2.1-1.i386.rpm \
 ocfs2-tools-1.2.1-1.i386.rpm
Preparing... ########################################### [100%]
1:ocfs2-tools ########################################### [ 33%]
2:ocfs2-2.6.9-22.EL ########################################### [ 67%]
3:ocfs2console ########################################### [100%]

Disable SELinux (RHEL4 U2 Only)

RHEL4 U2 users (CentOS 4.2 is based on RHEL4 U2) are advised that OCFS2 currently does not work with SELinux enabled. If you are using RHEL4 U2 (which includes you, since you are using CentOS 4.2 here) you will need to disable SELinux (using tool system-config-securitylevel) to get the O2CB service to execute.

To disable SELinux, run the "Security Level Configuration" GUI utility:

# /usr/bin/system-config-securitylevel &

This will bring up the following screen:

Figure 6 Security Level Configuration Opening Screen

Now, click the SELinux tab and check off the "Enabled" checkbox. After clicking on [OK], you will be presented with a warning dialog. Simply acknowledge this warning by clicking "Yes". Your screen should now look like the following after disabling the SELinux option:

Figure 7 SELinux Disabled

After making this change on both nodes in the cluster, each node will need to be rebooted to implement the change:

# init 6

Configure OCFS2

The next step is to generate and configure the /etc/ocfs2/cluster.conf file on each node in the cluster. The easiest way to accomplish this is to run the GUI tool ocfs2console. In this section, we will not only create and configure the /etc/ocfs2/cluster.conf file using ocfs2console, but will also create and start the cluster stack O2CB. When the /etc/ocfs2/cluster.conf file is not present, (as will be the case in our example), the ocfs2console tool will create this file along with a new cluster stack service (O2CB) with a default cluster name of ocfs2. This will need to be done on all nodes in the cluster as the root user account:

$ su -
# ocfs2console &
      

Figure 8 ocfs2console GUI

Using the ocfs2console GUI tool, perform the following steps:

1. Select [Cluster] -> [Configure Nodes...]. This will start the OCFS Cluster Stack (Figure 9) and bring up the "Node Configuration" dialog.
2. On the "Node Configuration" dialog, click the [Add] button.
   • This will bring up the "Add Node" dialog.
   • In the "Add Node" dialog, enter the Host name and IP address for the first node in the cluster. Leave the IP Port set to its default value of 7777. In my example, I added both nodes using linux1 / 192.168.1.100 for the first node and linux2 / 192.168.1.101 for the second node.
   • Click [Apply] on the "Node Configuration" dialog - All nodes should now be "Active" as shown in Figure 10.
   • Click [Close] on the "Node Configuration" dialog.
3. After verifying all values are correct, exit the application using [File] -> [Quit]. This needs to be performed on all nodes in the cluster.

Figure 9. Starting the OCFS2 Cluster Stack

The following dialog show the OCFS2 settings I used for the node linux1 and linux2:

Figure 10 Configuring Nodes for OCFS2

After exiting the ocfs2console, you will have a /etc/ocfs2/cluster.conf similar to the following. This process needs to be completed on all nodes in the cluster and the OCFS2 configuration file should be exactly the same for all of the nodes:

node:
 ip_port = 7777
 ip_address = 192.168.1.100
 number = 0
 name = linux1
 cluster = ocfs2

node:
 ip_port = 7777
 ip_address = 192.168.1.101
 number = 1
 name = linux2
 cluster = ocfs2

cluster:
 node_count = 2
 name = ocfs2

O2CB Cluster Service

Before we can do anything with OCFS2 like formatting or mounting the file system, we need to first have OCFS2's cluster stack, O2CB, running (which it will be as a result of the configuration process performed above). The stack includes the following services:

• NM: Node Manager that keep track of all the nodes in the cluster.conf
• HB: Heart beat service that issues up/down notifications when nodes join or leave the cluster
• TCP: Handles communication between the nodes
• DLM: Distributed lock manager that keeps track of all locks, its owners and status
• CONFIGFS: User space driven configuration file system mounted at /config
• DLMFS: User space interface to the kernel space DLM

All of the above cluster services have been packaged in the o2cb system service (/etc/init.d/o2cb). Here is a short listing of some of the more useful commands and options for the o2cb system service.

• /etc/init.d/o2cb status

  Module "configfs": Not loaded
  Filesystem "configfs": Not mounted
  Module "ocfs2_nodemanager": Not loaded
  Module "ocfs2_dlm": Not loaded
  Module "ocfs2_dlmfs": Not loaded
  Filesystem "ocfs2_dlmfs": Not mounted

  Note that with this example, all of the services are not loaded. I did an "unload" right before executing the "status" option. If you were to check the status of the o2cb service immediately after configuring OCFS using ocfs2console utility, they would all be loaded.

• /etc/init.d/o2cb load

  Loading module "configfs": OK
  Mounting configfs filesystem at /config: OK
  Loading module "ocfs2_nodemanager": OK
  Loading module "ocfs2_dlm": OK
  Loading module "ocfs2_dlmfs": OK
  Mounting ocfs2_dlmfs filesystem at /dlm: OK

  Loads all OCFS modules.

• /etc/init.d/o2cb online ocfs2

  Starting cluster ocfs2: OK

  The above command will online the cluster we created, ocfs2.

• /etc/init.d/o2cb offline ocfs2

  Unmounting ocfs2_dlmfs filesystem: OK
  Unloading module "ocfs2_dlmfs": OK
  Unmounting configfs filesystem: OK
  Unloading module "configfs": OK

  The above command will offline the cluster we created, ocfs2.

• /etc/init.d/o2cb unload

  Cleaning heartbeat on ocfs2: OK
  Stopping cluster ocfs2: OK

  The above command will unload all OCFS modules.

Configure O2CB to Start on Boot

You now need to configure the on-boot properties of the OC2B driver so that the cluster stack services will start on each boot. All the tasks within this section will need to be performed on both nodes in the cluster.

...
Mounting other filesystems:
 mount.ocfs2: Unable to access cluster service

Cannot initialize cluster mount.ocfs2:
 Unable to access cluster service Cannot initialize cluster [FAILED]
...

Before attempting to configure the on-boot properties:

• REMOVE the following lines in /etc/init.d/o2cb

  ### BEGIN INIT INFO
  # Provides: o2cb
  # Required-Start:
  # Should-Start:
  # Required-Stop:
  # Default-Start: 2 3 5
  # Default-Stop:
  # Description: Load O2CB cluster services at system boot.
  ### END INIT INFO
   

• Re-register the o2cb service.

  # chkconfig --del o2cb
  # chkconfig --add o2cb
  # chkconfig --list o2cb
  o2cb 0:off 1:off 2:on 3:on 4:on 5:on 6:off
  # ll /etc/rc3.d/*o2cb*
  lrwxrwxrwx 1 root root 14 Sep 29 11:56 /etc/rc3.d/S24o2cb -> ../init.d/o2cb

  The service should be S24o2cb in the default runlevel.

After resolving this bug, you can continue to set the on-boot properties as follows:

# /etc/init.d/o2cb offline ocfs2
# /etc/init.d/o2cb unload
# /etc/init.d/o2cb configure
Configuring the O2CB driver.
This will configure the on-boot properties of the O2CB driver.
The following questions will determine whether the driver is loaded on
boot. The current values will be shown in brackets ('[]'). Hitting
<ENTER> without typing an answer will keep that current value. Ctrl-C
will abort.
Load O2CB driver on boot (y/n) [n]: y
Cluster to start on boot (Enter "none" to clear) [ocfs2]: ocfs2
Writing O2CB configuration: OK
Loading module "configfs": OK
Mounting configfs filesystem at /config: OK
Loading module "ocfs2_nodemanager": OK
Loading module "ocfs2_dlm": OK
Loading module "ocfs2_dlmfs": OK
Mounting ocfs2_dlmfs filesystem at /dlm: OK
Starting cluster ocfs2: OK

Format the OCFS2 Filesystem

You can now start to make use of the partitions created in the section Create Partitions on the Shared FireWire Storage Device. (Well, at least the first partition!)

If the O2CB cluster is offline, start it. The format operation needs the cluster to be online, as it needs to ensure that the volume is not mounted on some node in the cluster.

Earlier in this document, we created the directory /u02/oradata/orcl under the section Create Mount Point for OCFS/Clusterware. This section contains the commands to create and mount the file system to be used for the Cluster Manager - /u02/oradata/orcl.

Unlike the other tasks in this section, creating the OCFS2 filesystem should only be executed on one node in the RAC cluster. You will be executing all commands in this section from linux1 only.

Note that it is possible to create and mount the OCFS2 file system using either the GUI tool ocfs2console or the command-line tool mkfs.ocfs2. From the ocfs2console utility, use the menu [Tasks] - [Format].

See the instructions below on how to create the OCFS2 file system using the command-line tool mkfs.ocfs2.

To create the filesystem, use the Oracle executable mkfs.ocfs2. For the purpose of this example, I run the following command only from linux1 as the root user account:

$ su -
# mkfs.ocfs2 -b 4K -C 32K -N 4 -L oradatafiles /dev/sda1
mkfs.ocfs2 1.2.1
Filesystem label=oradatafiles
Block size=4096 (bits=12)
Cluster size=32768 (bits=15)
Volume size=1011646464 (30873 clusters) (246984 blocks)
1 cluster groups (tail covers 30873 clusters, rest cover 30873 clusters)
Journal size=16777216
Initial number of node slots: 4
Creating bitmaps: done
Initializing superblock: done
Writing system files: done
Writing superblock: done
Formatting Journals: done
Writing lost+found: done
mkfs.ocfs2 successful

Mount the OCFS2 Filesystem

Now that the file system is created, you can mount it. Let's first do it using the command-line, then I'll show how to include it in the /etc/fstab to have it mount on each boot. Mounting the filesystem will need to be performed on all nodes in the Oracle RAC cluster as the root user account.

First, here is how to manually mount the OCFS2 file system from the command line. Remember, this needs to be performed as the root user account:

$ su -
# mount -t ocfs2 -o datavolume,nointr /dev/sda1 /u02/oradata/orcl

If the mount was successful, you will simply got your prompt back. You should, however, run the following checks to ensure the fil system is mounted correctly.

Let's use the mount command to ensure that the new filesystem is really mounted. This should be performed on all nodes in the RAC cluster:

# mount
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
none on /proc type proc (rw)
none on /sys type sysfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/hda1 on /boot type ext3 (rw)
none on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
cartman:SHARE2 on /cartman type nfs (rw,addr=192.168.1.120)
configfs on /config type configfs (rw)
ocfs2_dlmfs on /dlm type ocfs2_dlmfs (rw)
/dev/sda1 on /u02/oradata/orcl type ocfs2 (rw,_netdev,datavolume,nointr,heartbeat=local)

Any other type of volume, including an Oracle home (not used in this guide), should not be mounted with this mount option.

Configure OCFS to Mount Automatically at Startup

Let's review what you've done so far. You downloaded and installed OCFS2, which will be used to store the files needed by Cluster Manager files. After going through the install, you loaded the OCFS2 module into the kernel and then formatted the clustered filesystem. Finally, you mounted the newly created filesystem. This section walks through the steps responsible for mounting the new OCFS2 file system each time the machine(s) are booted.

Start by adding the following line to the /etc/fstab file on all nodes in the RAC cluster:

/dev/sda1 /u02/oradata/orcl ocfs2 _netdev,datavolume,nointr 0 0

Now, let's make sure that the ocfs2.ko kernel module is being loaded and that the file system will be mounted during the boot process.

If you have been following along with the examples in this article, the actions to load the kernel module and mount the OCFS2 file system should already be enabled. However, you should still check those options by running the following on all nodes in the RAC cluster as the root user account:

$ su -
# chkconfig --list o2cb
o2cb 0:off 1:off 2:on 3:on 4:on 5:on 6:off

Check Permissions on New OCFS2 Filesystem

Use the ls command to check ownership. The permissions should be set to 0775 with owner "oracle" and group "dba".

Let's first check the permissions:

# ls -ld /u02/oradata/orcl
drwxr-xr-x 3 root root 4096 Sep 29 12:11 /u02/oradata/orcl

# chown oracle.dba /u02/oradata/orcl
# chmod 775 /u02/oradata/orcl

# ls -ld /u02/oradata/orcl
drwxrwxr-x 3 oracle dba 4096 Sep 29 12:11 /u02/oradata/orcl

Adjust the O2CB Heartbeat Threshold

This is a very important section when configuring OCFS2 for use by Oracle Clusterware's two shared files on our FireWire drive. During testing, I was able to install and configure OCFS2, format the new volume, and finally install Oracle Clusterware (with its two required shared files; the voting disk and OCR file), located on the new OCFS2 volume. I was able to install Oracle Clusterware and see the shared drive; however, during my evaluation I was receiving many lock-ups and hanging after about 15 minutes when the Clusterware software was running on both nodes. It always varied on which node would hang (either linux1 or linux2 in my example). It also didn't matter whether there was a high I/O load or none at all for it to crash (hang).

Keep in mind that the configuration you are creating is a rather low-end setup being configured with slow disk access with regards to the FireWire drive. This is by no means a high-end setup and is susceptible to bogus timeouts.

After looking through the trace files for OCFS2, it was apparent that access to the voting disk was too slow (exceeding the O2CB heartbeat threshold) and causing the Oracle Clusterware software (and the node) to crash.

The solution I used was to simply increase the O2CB heartbeat threshold from its default setting of 7, to 601 (and in some cases as high as 901). This is a configurable parameter that is used to compute the time it takes for a node to "fence" itself.

First, let's see how to determine what the O2CB heartbeat threshold is currently set to. This can be done by querying the /proc file system as follows:

# cat /proc/fs/ocfs2_nodemanager/hb_dead_threshold
7

[fence time in seconds] = (O2CB_HEARTBEAT_THRESHOLD - 1) * 2

(7 - 1) * 2 = 12 seconds

(601 - 1) * 2 = 1200 seconds

Let's see now how to increase the O2CB heartbeat threshold from 7 to 601. This will need to be performed on both nodes in the cluster. You first need to modify the file /etc/sysconfig/o2cb and set O2CB_HEARTBEAT_THRESHOLD to 601:

# O2CB_ENABELED: 'true' means to load the driver on boot.
O2CB_ENABLED=true

# O2CB_BOOTCLUSTER: If not empty, the name of a cluster to start.
O2CB_BOOTCLUSTER=ocfs2

# O2CB_HEARTBEAT_THRESHOLD: Iterations before a node is considered dead.
O2CB_HEARTBEAT_THRESHOLD=601

After modifying the file /etc/sysconfig/o2cb, you need to alter the o2cb configuration. Again, this should be performed on all nodes in the cluster.

# umount /u02/oradata/orcl/
# /etc/init.d/o2cb unload
# /etc/init.d/o2cb configure
Load O2CB driver on boot (y/n) [y]: y
Cluster to start on boot (Enter "none" to clear) [ocfs2]: ocfs2
Writing O2CB configuration: OK
Loading module "configfs": OK
Mounting configfs filesystem at /config: OK
Loading module "ocfs2_nodemanager": OK
Loading module "ocfs2_dlm": OK
Loading module "ocfs2_dlmfs": OK
Mounting ocfs2_dlmfs filesystem at /dlm: OK
Starting cluster ocfs2: OK

# cat /proc/fs/ocfs2_nodemanager/hb_dead_threshold
601

Replace CFQ I/O Scheduler with the DEADLINE I/O Scheduler - (RHEL4 U2 and U3 Users)

A bug has been encountered with the default CFQ I/O scheduler which causes a process doing heavy I/O to temporarily starve out other processes. While this is not fatal for most environments, it is for OCFS2 as the heartbeat thread is expected to be r/w to the heartbeat area at least once every 12 seconds (default). A bug along with the fix has been filed with Red Hat. Red Hat is expected to have this fixed in RHEL4 U4 release. SLES9 SP3 2.5.6-7.257 includes this fix. Until this issue is resolved, one is advised to use the DEADLINE I/O scheduler. To use it, add "elevator=deadline" to the kernel command line found in the /boot/grub/grub.conf file. This will need to be performed on both nodes in the cluster:

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS-4 i386 (2.6.9-22.EL)
 root (hd0,0)
 kernel /vmlinuz-2.6.9-22.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet elevator=deadline
initrd /initrd-2.6.9-22.EL.img

After making this change, the system will need to be rebooted for the change to take effect. (See the next task)

Reboot Both Nodes

Before starting the next section, this would be a good place to reboot all of the nodes in the RAC cluster. When the machines come up, ensure that the cluster stack services are being loaded and the new OCFS2 file system is being mounted:

# mount
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
none on /proc type proc (rw)
none on /sys type sysfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/hda1 on /boot type ext3 (rw)
none on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
cartman:SHARE2 on /cartman type nfs (rw,addr=192.168.1.120)
configfs on /config type configfs (rw)
ocfs2_dlmfs on /dlm type ocfs2_dlmfs (rw)
/dev/sda1 on /u02/oradata/orcl type ocfs2 (rw,_netdev,datavolume,nointr,heartbeat=local)

# cat /proc/fs/ocfs2_nodemanager/hb_dead_threshold
601

# cat /proc/cmdline
ro root=/dev/VolGroup00/LogVol00 rhgb quiet elevator=deadline

How to Determine OCFS2 Version

To determine which version of OCFS2 is running, use:

# cat /proc/fs/ocfs2/version
OCFS2 1.2.3 Wed Jul 26 12:34:15 PDT 2006 (build 6b798aaadf626d3b137c3952809b2f38)

Most of the installation and configuration procedures should be performed on all nodes. Creating the ASM disks, however, will only need to be performed on a single node within the cluster.

In this section, you will configure ASM to be used as the filesystem / volume manager for all Oracle physical database files (data, online redo logs, control files, archived redo logs) and a Flash Recovery Area.

The ASM feature was introduced in Oracle Database 10g Release 1 and is used to alleviate the DBA from having to manage individual files and drives. ASM is built into the Oracle kernel and provides the DBA with a way to manage thousands of disk drives 24x7 for both single and clustered instances of Oracle. All the files and directories to be used for Oracle will be contained in a disk group. ASM automatically performs load balancing in parallel across all available disk drives to prevent hot spots and maximize performance, even with rapidly changing data usage patterns.

I start this section by first discussing the ASMLib 2.0 libraries and its associated driver for Linux plus other methods for configuring ASM with Linux. Next, I will provide instructions for downloading the ASM drivers (ASMLib Release 2.0) specific to your Linux kernel. Last, you will install and configure the ASMLib 2.0 drivers while finishing off the section with a demonstration of how to create the ASM disks.

If you would like to learn more about the ASMLib, visit www.oracle.com/technology/tech/linux/asmlib/install.html.

Methods for Configuring ASM with Linux (For Reference Only)

When I first started this guide, I wanted to focus on using ASM for all database files. I was curious to see how well ASM works with this test RAC configuration with regard to load balancing and fault tolerance.

There are two different methods to configure ASM on Linux:

• ASM with ASMLib I/O: This method creates all Oracle database files on raw block devices managed by ASM using ASMLib calls. Raw devices are not required with this method as ASMLib works with block devices.
• ASM with Standard Linux I/O: This method creates all Oracle database files on raw character devices managed by ASM using standard Linux I/O system calls. You will be required to create raw devices for all disk partitions used by ASM.

We will examine the "ASM with ASMLib I/O" method here.

Before discussing the installation and configuration details of ASMLib, however, I thought it would be interesting to talk briefly about the second method, "ASM with Standard Linux I/O." If you were to use this method (which is a perfectly valid solution, just not the method we will be implementing here), you should be aware that Linux does not use raw devices by default. Every Linux raw device you want to use must be bound to the corresponding block device using the raw driver. For example, if you wanted to use the partitions we've created, (/dev/sda2, /dev/sda3, and /dev/sda4), you would need to perform the following tasks:

1. Edit the file /etc/sysconfig/rawdevices as follows:

   # raw device bindings
   # format: <rawdev> <major> <minor>
   # <rawdev> <blockdev>
   # example: /dev/raw/raw1 /dev/sda1
   # /dev/raw/raw2 8 5
   /dev/raw/raw2 /dev/sda2
   /dev/raw/raw3 /dev/sda3
   /dev/raw/raw4 /dev/sda4
   

   The raw device bindings will be created on each reboot.
2. You would then want to change ownership of all raw devices to the "oracle" user account:

   # chown oracle:dba /dev/raw/raw2; chmod 660 /dev/raw/raw2
   # chown oracle:dba /dev/raw/raw3; chmod 660 /dev/raw/raw3
   # chown oracle:dba /dev/raw/raw4; chmod 660 /dev/raw/raw4
             

3. The last step is to reboot the server to bind the devices or simply restart the rawdevices service:

   # service rawdevices restart
             

As I mentioned earlier, the above example was just to demonstrate that there is more than one method for using ASM with Linux. Now let's move on to the method that will be used for this article, "ASM with ASMLib I/O."

Download the ASMLib 2.0 Packages

First download the latest ASMLib 2.0 libraries and the driver from OTN. At the time of this writing, the latest release of the ASMLib driver was 2.0.3-1. Like OCFS2, you need to download the version for the Linux kernel and number of processors on the machine. You are using kernel 2.6.9-22.EL #1 on single-processor machines:

# uname -a
Linux linux1 2.6.9-22.EL #1 Sat Oct 8 17:48:27 CDT 2005 i686 i686 i386 GNU/Linux

• oracleasm-2.6.9-22.EL-2.0.3-1.i686.rpm - (for single processor)
  -OR-
  
• oracleasm-2.6.9-22.ELsmp-2.0.3-1.i686.rpm - (for multiple processors)
  -OR-
  
• oracleasm-2.6.9-22.ELhugemem-2.0.3-1.i686.rpm - (for hugemem)

You will also need to download the following ASMLib tools:

• oracleasmlib-2.0.2-1.i386.rpm - (Userspace library)
• oracleasm-support-2.0.3-1.i386.rpm - (Driver support files)

Install ASMLib 2.0 Packages

This installation needs to be performed on all nodes as the root user account:

$ su -
# rpm -Uvh oracleasm-2.6.9-22.EL-2.0.3-1.i686.rpm \
 oracleasmlib-2.0.2-1.i386.rpm \
 oracleasm-support-2.0.3-1.i386.rpm
Preparing... ########################################### [100%]
1:oracleasm-support ########################################### [ 33%]
2:oracleasm-2.6.9-22.EL ########################################### [ 67%]
3:oracleasmlib ########################################### [100%]

Configure and Loading the ASMLib 2.0 Packages

Now that you downloaded and installed the ASMLib Packages for Linux, you need to configure and load the ASM kernel module. This task needs to be run on all nodes as root:

$ su -
# /etc/init.d/oracleasm configure
Configuring the Oracle ASM library driver.
This will configure the on-boot properties of the Oracle ASM library
driver. The following questions will determine whether the driver is
loaded on boot and what permissions it will have. The current values
will be shown in brackets ('[]'). Hitting <ENTER> without typing an
answer will keep that current value. Ctrl-C will abort.
Default user to own the driver interface []: oracle
Default group to own the driver interface []: dba
Start Oracle ASM library driver on boot (y/n) [n]: y
Fix permissions of Oracle ASM disks on boot (y/n) [y]: y
Writing Oracle ASM library driver configuration: [ OK ]
Creating /dev/oracleasm mount point: [ OK ]
Loading module "oracleasm": [ OK ]
Mounting ASMlib driver filesystem: [ OK ]
Scanning system for ASM disks: [ OK ]

Create ASM Disks for Oracle

In Section 10, you created three Linux partitions to be used for storing Oracle database files like online redo logs, database files, control files, archived redo log files, and a flash recovery area.

Here is a list of those partitions we created for use by ASM:

The last task in this section it to create the ASM Disks. Creating the ASM disks only needs to be done on one node as the root user account. I will be running these commands on linux1. On the other nodes, you will need to perform a scandisk to recognize the new volumes. When that is complete, you should then run the oracleasm listdisks command on all nodes to verify that all ASM disks were created and available.

$ su -
# /etc/init.d/oracleasm createdisk VOL1 /dev/sda2
Marking disk "/dev/sda2" as an ASM disk [ OK ]

# /etc/init.d/oracleasm createdisk VOL2 /dev/sda3
Marking disk "/dev/sda3" as an ASM disk [ OK ] 

# /etc/init.d/oracleasm createdisk VOL3 /dev/sda4
Marking disk "/dev/sda4" as an ASM disk [ OK ]

Note: If you are repeating this guide using the same hardware (actually, the same shared drive), you may get a failure when attempting to create the ASM disks. If you do receive a failure, try listing all ASM disks using:

# /etc/init.d/oracleasm listdisks
VOL1
VOL2
VOL3

As you can see, the results show that I have three volumes already defined. If you have the three volumes already defined from a previous run, go ahead and remove them using the following commands and then creating them again using the above (oracleasm createdisk) commands:

# /etc/init.d/oracleasm deletedisk VOL1
Removing ASM disk "VOL1" [ OK ]
# /etc/init.d/oracleasm deletedisk VOL2
Removing ASM disk "VOL2" [ OK ]
# /etc/init.d/oracleasm deletedisk VOL3
Removing ASM disk "VOL3" [ OK ]

# /etc/init.d/oracleasm scandisks
Scanning system for ASM disks [ OK ]

You can now test that the ASM disks were successfully created by using the following command on all nodes as the root user account:

# /etc/init.d/oracleasm listdisks
VOL1
VOL2
VOL3

The following download procedures only need to be performed on one node in the cluster!

The next logical step is to install Oracle Clusterware Release 2 (10.2.0.1.0), Oracle Database 10g Release 2 (10.2.0.1.0), and finally the Oracle Database 10g Companion CD Release 2 (10.2.0.1.0) for Linux x86 software. However, you must first download and extract the required Oracle software packages from OTN.

You will be downloading and extracting the required software from Oracle to only one of the Linux nodes in the cluster—namely, linux1. You will perform all installs from this machine. The Oracle installer will copy the required software packages to all other nodes in the RAC configuration we set up in Section 13.

Login to one of the nodes in the Linux RAC cluster as the oracle user account. In this example, you will be downloading the required Oracle software to linux1 and saving them to /u01/app/oracle/orainstall.

Downloading and Extracting the Software

First, download the Oracle Clusterware Release 2 (10.2.0.1.0), Oracle Database 10g Release 2 (10.2.0.1.0), and Oracle Database 10g Companion CD Release 2 (10.2.0.1.0) software for Linux x86. All downloads are available from the same page.

As the oracle user account, extract the three packages you downloaded to a temporary directory. In this example, we will use /u01/app/oracle/orainstall.

Extract the Oracle Clusterware package as follows:

# su - oracle
$ cd ~oracle/orainstall
$ unzip 10201_clusterware_linux32.zip
      

$ cd ~oracle/orainstall
$ unzip 10201_database_linux32.zip
      

$ cd ~oracle/orainstall
$ unzip 10201_companion_linux32.zip