Oracle 10g RAC On Linux Using NFS

This article describes the installation of Oracle 10g release 2 (10.2.0.1) RAC on Linux (Oracle Enterprise Linux 4.5) using NFS to provide the shared storage.

• Introduction
• Download Software
• Operating System Installation
• Oracle Installation Prerequisites
• Create Shared Disks
• Install the Clusterware Software
• Install the Database Software
• Create a Database using the DBCA
• TNS Configuration
• Check the Status of the RAC
• Direct and Asynchronous I/O

Introduction

NFS is an abbreviation of Network File System, a platform. independent technology created by Sun Microsystems that allows shared access to files stored on computers via an interface called the Virtual File System (VFS) that runs on top of TCP/IP. Computers that share files are considered NFS servers, while those that access shared files are considered NFS clients. An individual computer can be either an NFS server, a NFS client or both.

We can use NFS to provide shared storage for a RAC installation. In a production environment we would expect the NFS server to be a NAS, but for testing it can just as easily be another server, or even one of the RAC nodes itself.

To cut costs, this articles uses one of the RAC nodes as the source of the shared storage. Obviously, this means if that node goes down the whole database is lost, so it's not a sensible idea to do this if you are testing high availability. If you have access to a NAS or a third server you can easily use that for the shared storage, making the whole solution much more resilient. Whichever route you take, the fundamentals of the installation are the same.

This article was inspired by the blog postings of Kevin Closson.

Download Software

Download the following software.

• Oracle Enterprise Linux
• Oracle 10g (10.2.0.1) CRS and DB software

Operating System Installation

This article uses Oracle Enterprise Linux 4.5, but it will work equally well on CentOS 4 or Red Hat Enterprise Linux (RHEL) 4. A general pictorial guide to the operating system installation can be found here. More specifically, it should be a server installation with a minimum of 2G swap, firewall and secure Linux disabled and the following package groups installed:

• X Window System
• GNOME Desktop Environment
• Editors
• Graphical Internet
• Server Configuration Tools
• FTP Server
• Development Tools
• Legacy Software Development
• Administration Tools
• System Tools

To be consistent with the rest of the article, the following information should be set during the installation:

RAC1:

• hostname: rac1.localdomain
• IP Address eth0: 192.168.2.101 (public address)
• Default Gateway eth0: 192.168.2.1 (public address)
• IP Address eth1: 192.168.0.101 (private address)
• Default Gateway eth1: none

RAC2:

• hostname: rac2.localdomain
• IP Address eth0: 192.168.2.102 (public address)
• Default Gateway eth0: 192.168.2.1 (public address)
• IP Address eth1: 192.168.0.102 (private address)
• Default Gateway eth1: none

You are free to change the IP addresses to suit your network, but remember to stay consistent with those adjustments throughout the rest of the article.

Once the basic installation is complete, install the following packages whilst logged in as the root user.

# From Oracle Enterprise Linux 4.5 Disk 1
cd /media/cdrecorder/CentOS/RPMS
rpm -Uvh setarch-1*
rpm -Uvh compat-libstdc++-33-3*
rpm -Uvh make-3*
rpm -Uvh glibc-2*
cd /
eject

# From Oracle Enterprise Linux 4.5 Disk 2
cd /media/cdrecorder/CentOS/RPMS
rpm -Uvh openmotif-2*
rpm -Uvh compat-db-4*
rpm -Uvh gcc-3*
cd /
eject

# From Oracle Enterprise Linux 4.5 Disk 3
cd /media/cdrecorder/CentOS/RPMS
rpm -Uvh libaio-0*
rpm -Uvh rsh-*
rpm -Uvh compat-gcc-32-3*
rpm -Uvh compat-gcc-32-c++-3*
rpm -Uvh openmotif21*
cd /
eject

Oracle Installation Prerequisites

Perform. the following steps whilst logged into the RAC1 virtual machine as the root user.

The /etc/hosts file must contain the following information.

127.0.0.1       localhost.localdomain   localhost
# Public
192.168.2.101   rac1.localdomain        rac1
192.168.2.102   rac2.localdomain        rac2
#Private
192.168.0.101   rac1-priv.localdomain   rac1-priv
192.168.0.102   rac2-priv.localdomain   rac2-priv
#Virtual
192.168.2.111   rac1-vip.localdomain    rac1-vip
192.168.2.112   rac2-vip.localdomain    rac2-vip
#NAS
192.168.2.101   nas1.localdomain        nas1

Notice that the NAS1 entry is actually pointing to the RAC1 node. If you are using a real NAS or a third server to provide your shared storage put the correct IP address into the file.

Add the following lines to the /etc/sysctl.conf file.

kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128
#fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000
#net.core.rmem_default=262144
#net.core.rmem_max=262144
#net.core.wmem_default=262144
#net.core.wmem_max=262144

# Additional and amended parameters suggested by Kevin Closson
net.core.rmem_default = 524288
net.core.wmem_default = 524288
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.ipfrag_high_thresh=524288
net.ipv4.ipfrag_low_thresh=393216
net.ipv4.tcp_rmem=4096 524288 16777216
net.ipv4.tcp_wmem=4096 524288 16777216
net.ipv4.tcp_timestamps=0
net.ipv4.tcp_sack=0
net.ipv4.tcp_window_scaling=1
net.core.optmem_max=524287
net.core.netdev_max_backlog=2500
sunrpc.tcp_slot_table_entries=128
sunrpc.udp_slot_table_entries=128
net.ipv4.tcp_mem=16384 16384 16384

Run the following command to change the current kernel parameters.

/sbin/sysctl -p

Add the following lines to the /etc/security/limits.conf file.

*               soft    nproc   2047
*               hard    nproc   16384
*               soft    nofile  1024
*               hard    nofile  65536

Add the following line to the /etc/pam.d/login file, if it does not already exist.

session    required     /lib/security/pam_limits.so

Disable secure linux by editing the /etc/selinux/config file, making sure the SELINUX flag is set as follows.

SELINUX=disabled

Alternatively, this alteration can be done using the GUI tool (Applications > System Settings > Security Level). Click on the SELinux tab and disable the feature.

Set the hangcheck kernel module parameters by adding the following line to the /etc/modprobe.conf file.

options hangcheck-timer hangcheck_tick=30 hangcheck_margin=180

To load the module immediately, execute "modprobe -v hangcheck-timer".

Create the new groups and users.

groupadd oinstall
groupadd dba
groupadd oper

useradd -g oinstall -G dba oracle
passwd oracle

During the installation, both RSH and RSH-Server were installed. Enable remote shell and rlogin by doing the following.

chkconfig rsh on
chkconfig rlogin on
service xinetd reload

Create the /etc/hosts.equiv file as the root user.

touch /etc/hosts.equiv
chmod 600 /etc/hosts.equiv
chown root:root /etc/hosts.equiv

Edit the /etc/hosts.equiv file to include all the RAC nodes:

+rac1 oracle
+rac2 oracle
+rac1-priv oracle
+rac2-priv oracle

Login as the oracle user and add the following lines at the end of the .bash_profile file.

# Oracle Settings
TMP=/tmp; export TMP
TMPDIR=$TMP; export TMPDIR

ORACLE_BASE=/u01/app/oracle; export ORACLE_BASE
ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1; export ORACLE_HOME
ORACLE_SID=RAC1; export ORACLE_SID
ORACLE_TERM=xterm; export ORACLE_TERM
PATH=/usr/sbin:$PATH; export PATH
PATH=$ORACLE_HOME/bin:$PATH; export PATH

LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/JRE:$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH

if [ $USER = "oracle" ]; then
  if [ $SHELL = "/bin/ksh" ]; then
    ulimit -p 16384
    ulimit -n 65536
  else
    ulimit -u 16384 -n 65536
  fi
fi

Remember to set the ORACLE_SID to RAC2 on the second node.

Create Shared Disks

First we need to set up some NFS shares. In this case we will do this on the RAC1 node, but you can do the on a NAS or a third server if you have one available. On the RAC1 node create the following directories.

mkdir /share1
mkdir /share2

Add the following lines to the /etc/exports file.

/share1                  *(rw,sync,no_wdelay,insecure_locks,no_root_squash)
/share2                  *(rw,sync,no_wdelay,insecure_locks,no_root_squash)

Run the following command to export the NFS shares.

chkconfig nfs on
service nfs restart

On both RAC1 and RAC2 create some mount points to mount the NFS shares to.

mkdir /u01
mkdir /u02

Add the following lines to the "/etc/fstab" file. The mount options are suggestions from Kevin Closson.

nas1:/share1  /u01  nfs  rw,bg,hard,nointr,tcp,vers=3,timeo=300,rsize=32768,wsize=32768,actimeo=0  0 0
nas1:/share2  /u02  nfs  rw,bg,hard,nointr,tcp,vers=3,timeo=300,rsize=32768,wsize=32768,actimeo=0  0 0

Mount the NFS shares on both servers.

mount /u01
mount /u02

Create the shared CRS Configuration and Voting Disk files.

touch /u01/crs_configuration
touch /u01/voting_disk

Create the directories in which the Oracle software will be installed.

mkdir -p /u01/crs/oracle/product/10.2.0/crs
mkdir -p /u01/app/oracle/product/10.2.0/db_1
mkdir -p /u01/oradata
chown -R oracle:oinstall /u01 /u02

Install the Clusterware Software

Place the clusterware and database software in the /u02 directory and unzip it.

cd /u02
unzip 10201_clusterware_linux32.zip
unzip 10201_database_linux32.zip

Login to RAC1 as the oracle user and start the Oracle installer.

cd /u02/clusterware
./runInstaller

On the "Welcome" screen, click the "Next" button.



Accept the default inventory location by clicking the "Next" button.



Enter the appropriate name and path for the Oracle Home and click the "Next" button.



Wait while the prerequisite checks are done. If you have any failures correct them and retry the tests before clicking the "Next" button.



The "Specify Cluster Configuration" screen shows only the RAC1 node in the cluster. Click the "Add" button to continue.



Enter the details for the RAC2 node and click the "OK" button.



Click the "Next" button to continue.



The "Specific Network Interface Usage" screen defines how each network interface will be used. Highlight the "eth0" interface and click the "Edit" button.



Set the "eht0" interface type to "Public" and click the "OK" button.



Leave the "eth1" interface as private and click the "Next" button.



Click the "External Redundancy" option, enter "/u01/ocr_configuration" as the OCR Location and click the "Next" button. To have greater redundancy we would need to define another shared disk for an alternate location.



Click the "External Redundancy" option, enter "/u01/voting_disk" as the Voting Disk Location and click the "Next" button. To have greater redundancy we would need to define another shared disk for an alternate location.



On the "Summary" screen, click the "Install" button to continue.



Wait while the installation takes place.



Once the install is complete, run the orainstRoot.sh and root.sh scripts on both nodes as directed on the following screen.



The output from the orainstRoot.sh file should look something like that listed below.

# cd /u01/app/oracle/oraInventory
# ./orainstRoot.sh
Changing permissions of /u01/app/oracle/oraInventory to 770.
Changing groupname of /u01/app/oracle/oraInventory to oinstall.
The execution of the script. is complete
#

The output of the root.sh will vary a little depending on the node it is run on. The following text is the output from the RAC1 node.

# cd /u01/crs/oracle/product/10.2.0/crs
# ./root.sh
WARNING: directory '/u01/crs/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/crs/oracle/product' is not owned by root
WARNING: directory '/u01/crs/oracle' is not owned by root
WARNING: directory '/u01/crs' is not owned by root
WARNING: directory '/u01' is not owned by root
Checking to see if Oracle CRS stack is already configured
/etc/oracle does not exist. Creating it now.

Setting the permissions on OCR backup directory
Setting up NS directories
Oracle Cluster Registry configuration upgraded successfully
WARNING: directory '/u01/crs/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/crs/oracle/product' is not owned by root
WARNING: directory '/u01/crs/oracle' is not owned by root
WARNING: directory '/u01/crs' is not owned by root
WARNING: directory '/u01' is not owned by root
assigning default hostname rac1 for node 1.
assigning default hostname rac2 for node 2.
Successfully accumulated necessary OCR keys.
Using ports: CSS=49895 CRS=49896 EVMC=49898 and EVMR=49897.
node :   
node 1: rac1 rac1-priv rac1
node 2: rac2 rac2-priv rac2
Creating OCR keys for user 'root', privgrp 'root'..
Operation successful.
Now formatting voting device: /u01/voting_disk
Format of 1 voting devices complete.
Startup will be queued to init within 90 seconds.
Adding daemons to inittab
Expecting the CRS daemons to be up within 600 seconds.
CSS is active on these nodes.
        rac1
CSS is inactive on these nodes.
        rac2
Local node checking complete.
Run root.sh on remaining nodes to start CRS daemons.
#

Ignore the directory ownership warnings. We should really use a separate directory structure for the clusterware so it can be owned by the root user, but it has little effect on the finished results.

The output from the RAC2 node is listed below.

# /u01/crs/oracle/product/10.2.0/crs
# ./root.sh
WARNING: directory '/u01/crs/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/crs/oracle/product' is not owned by root
WARNING: directory '/u01/crs/oracle' is not owned by root
WARNING: directory '/u01/crs' is not owned by root
WARNING: directory '/u01' is not owned by root
Checking to see if Oracle CRS stack is already configured
/etc/oracle does not exist. Creating it now.

Setting the permissions on OCR backup directory
Setting up NS directories
Oracle Cluster Registry configuration upgraded successfully
WARNING: directory '/u01/crs/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/crs/oracle/product' is not owned by root
WARNING: directory '/u01/crs/oracle' is not owned by root
WARNING: directory '/u01/crs' is not owned by root
WARNING: directory '/u01' is not owned by root
clscfg: EXISTING configuration version 3 detected.
clscfg: version 3 is 10G Release 2.
assigning default hostname rac1 for node 1.
assigning default hostname rac2 for node 2.
Successfully accumulated necessary OCR keys.
Using ports: CSS=49895 CRS=49896 EVMC=49898 and EVMR=49897.
node :   
node 1: rac1 rac1-priv rac1
node 2: rac2 rac2-priv rac2
clscfg: Arguments check out successfully.

NO KEYS WERE WRITTEN. Supply -force parameter to override.
-force is destructive and will destroy any previous cluster
configuration.
Oracle Cluster Registry for cluster has already been initialized
Startup will be queued to init within 90 seconds.
Adding daemons to inittab
Expecting the CRS daemons to be up within 600 seconds.
CSS is active on these nodes.
        rac1
        rac2
CSS is active on all nodes.
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Oracle CRS stack installed and running under init(1M)
Running vipca(silent) for configuring nodeapps
The given interface(s), "eth0" is not public. Public interfaces should be used to configure virtual IPs.
#

Here you can see that some of the configuration steps are omitted as they were done by the first node. In addition, the final part of the script. ran the Virtual IP Configuration Assistant (VIPCA) in silent mode, but it failed. This is because my public IP addresses are actually within the "192.168.255.255" range which is a private IP range. If you were using "legal" IP addresses you would not see this and you could ignore the following VIPCA steps.

Run the VIPCA manually as the root user on the RAC2 node using the following command.

# cd /u01/crs/oracle/product/10.2.0/crs/bin
# ./vipca

Click the "Next" button on the VIPCA welcome screen.



Highlight the "eth0" interface and click the "Next" button.



Enter the vitual IP alias and address for each node. Once you enter the first alias, the remaining values should default automatically. Click the "Next" button to continue.



Accept the summary information by clicking the "Finish" button.



Wait until the configuration is complete, then click the "OK" button.



Accept the VIPCA results by clicking the "Exit" button.



You should now return to the "Execute Configuration Scripts" screen on RAC1 and click the "OK" button.



Wait for the configuration assistants to complete.



When the installation is complete, click the "Exit" button to leave the installer.



The clusterware installation is now complete.

Install the Database Software

Login to RAC1 as the oracle user and start the Oracle installer.

cd /u02/database
./runInstaller

On the "Welcome" screen, click the "Next" button.



Select the "Enterprise Edition" option and click the "Next" button.



Enter the name and path for the Oracle Home and click the "Next" button.



Select the "Cluster Install" option and make sure both RAC nodes are selected, the click the "Next" button.



Wait while the prerequisite checks are done. If you have any failures correct them and retry the tests before clicking the "Next" button.



Select the "Install database Software only" option, then click the "Next" button.



On the "Summary" screen, click the "Install" button to continue.



Wait while the database software installs.



Once the installation is complete, wait while the configuration assistants run.



Execute the "root.sh" scripts on both nodes, as instructed on the "Execute Configuration scripts" screen, then click the "OK" button.



When the installation is complete, click the "Exit" button to leave the installer.

Create a Database using the DBCA

Login to RAC1 as the oracle user and start the Database Configuration Assistant.

dbca

On the "Welcome" screen, select the "Oracle Real Application Clusters database" option and click the "Next" button.



Select the "Create a Database" option and click the "Next" button.



Highlight both RAC nodes and click the "Next" button.



Select the "Custom Database" option and click the "Next" button.



Enter the values "RAC.WORLD" and "RAC" for the Global Database Name and SID Prefix respectively, then click the "Next" button.



Accept the management options by clicking the "Next" button. If you are attempting the installation on a server with limited memory, you may prefer not to configure Enterprise Manager at this time.



Enter database passwords then click the "Next" button.



Select the "Cluster File System" option, then click the "Next" button.



Select the "Use Oracle-Managed Files" option and enter "/u01/oradata/" as the database location, then click the "Next" button.



Check the "Specify Flash Recovery Area" option and accept the default location by clicking the "Next" button.



Uncheck all but the "Enterprise Manager Repository" option, then click the "Standard Database Components..." button.



Uncheck all but the "Oracle JVM" option, then click the "OK" button, followed by the "Next" button on the previous screen. If you are attempting the installation on a server with limited memory, you may prefer not to install the JVM at this time.



Accept the current database services configuration by clicking the "Next" button.



Select the "Custom" memory management option and accept the default settings by clicking the "Next" button.



Accept the database storage settings by clicking the "Next" button.



Accept the database creation options by clicking the "Finish" button.



Accept the summary information by clicking the "OK" button.



Wait while the database is created.



Once the database creation is complete you are presented with the following screen. Make a note of the information on the screen and click the "Exit" button.



The RAC database creation is now complete.

TNS Configuration

Once the installation is complete, the "$ORACLE_HOME/network/admin/listener.ora" file in the shared $ORACLE_HOME will contain the following entries.

LISTENER_RAC2 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = rac2-vip.lynx.co.uk)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.2.102)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
    )
  )

LISTENER_RAC1 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = rac1-vip.lynx.co.uk)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.2.101)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
    )
  )

The shared "$ORACLE_HOME/network/admin/tnsnames.ora" file will contain the following entries.

RAC =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac1-vip.lynx.co.uk)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac2-vip.lynx.co.uk)(PORT = 1521))
    (LOAD_BALANCE = yes)
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = RAC.WORLD)
    )
  )

LISTENERS_RAC =
  (ADDRESS_LIST =
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac1-vip.lynx.co.uk)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac2-vip.lynx.co.uk)(PORT = 1521))
  )

RAC2 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac2-vip.lynx.co.uk)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = RAC.WORLD)
      (INSTANCE_NAME = RAC2)
    )
  )

RAC1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = rac1-vip.lynx.co.uk)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = RAC.WORLD)
      (INSTANCE_NAME = RAC1)
    )
  )

This configuration allows direct connections to specific instance, or using a load balanced connection to the main service.

$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Apr 18 12:27:11 2006

Copyright (c) 1982, 2005, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options

SQL> CONN sys/password@rac1 AS SYSDBA
Connected.
SQL> SELECT instance_name, host_name FROM v$instance;

INSTANCE_NAME    HOST_NAME
---------------- ----------------------------------------------------------------
RAC1             rac1.localdomain

SQL> CONN sys/password@rac2 AS SYSDBA
Connected.
SQL> SELECT instance_name, host_name FROM v$instance;

INSTANCE_NAME    HOST_NAME
---------------- ----------------------------------------------------------------
RAC2             rac2.localdomain

SQL> CONN sys/password@rac AS SYSDBA
Connected.
SQL> SELECT instance_name, host_name FROM v$instance;

INSTANCE_NAME    HOST_NAME
---------------- ----------------------------------------------------------------
RAC1             rac1.localdomain

SQL>

Check the Status of the RAC

There are several ways to check the status of the RAC. The srvctl utility shows the current configuration and status of the RAC database.

$ srvctl config database -d RAC
rac1 RAC1 /u01/app/oracle/product/10.2.0/db_1
rac2 RAC2 /u01/app/oracle/product/10.2.0/db_1
$

$ srvctl status database -d RAC
Instance RAC1 is running on node rac1
Instance RAC2 is running on node rac2
$

The V$ACTIVE_INSTANCES view can also display the current status of the instances.

$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Apr 18 12:15:15 2006

Copyright (c) 1982, 2005, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options

SQL> SELECT * FROM v$active_instances;

INST_NUMBER INST_NAME
----------- ------------------------------------------------------------
          1 rac1.localdomain:RAC1
          2 rac2.localdomain:RAC2

SQL>

Finally, the GV$ allow you to display global information for the whole RAC.

SQL> SELECT inst_id, username, sid, serial# FROM gv$session WHERE username IS NOT NULL;

   INST_ID USERNAME                              SID    SERIAL#
---------- ------------------------------ ---------- ----------
         1 SYS                                   127          2
         1 SYS                                   128         28
         1 SYS                                   130         10
         1 SYS                                   131          4
         1 SYS                                   133          9
         1 DBSNMP                                134         27
         1 DBSNMP                                135          1
         1 SYS                                   153        122
         2 SYSMAN                                120        243
         2 DBSNMP                                122         37
         2 DBSNMP                                124         93

   INST_ID USERNAME                              SID    SERIAL#
---------- ------------------------------ ---------- ----------
         2 SYSMAN                                125          2
         2 SYSMAN                                127          6
         2 SYS                                   128         26
         2 SYS                                   129         30
         2 SYS                                   130          3
         2 SYS                                   133        149
         2 SYSMAN                                134         58
         2 SYS                                   136         32

19 rows selected.

SQL>

If you have configured Enterprise Manager, it can be used to view the configuration and current status of the database.

Direct and Asynchronous I/O

Remember to use direct I/O and asynchronous I/O to improve performance. Direct I/O has been supported over NFS for some time, but support for asynchronous I/O over NFS was only introduced in RHEL 4 Update 3 (and its clones), so you need to use an up to date version of your Linux distribution to take advantage of this feature.

You can get details about this Direct and Asynchronous I/O by following the link.

For more information see:

• Oracle 10g RAC On Linux Using VMware Server
• Oracle Database 10g Release 2 (10.2.0.1) RAC Installation On Windows 2003 Using VMware Server
• Build Your Own Oracle RAC 10g Release 2 Cluster on Linux and FireWire
• Installation Guide for Linux x86 (10.2)
• Oracle Clusterware and Oracle Real Application Clusters Installation Guide for Linux (10.2)
• Direct and Asynchronous I/O

Hope this helps. Regards Tim...