Oracle RAC allows multiple computers to run Oracle RDBMS software simultaneously while accessing a single database, thus providing a clustered database. In a non-RAC Oracle database, a single instance accesses a single database. The database consists of a collection of data files; control files, and redo logs located on disk. The instance comprises the collection of Oracle-related memory and operating system processes that run on a computer system.

In an Oracle RAC environment, two or more computers (each with an instance) concurrently access a single database. This allows an application or user to connect to either computer and have access to a single coordinated set of data.

Oracle RAC One Node is a new option available with Oracle Database 11g Release 2. Oracle RAC One Node is a single instance of an Oracle RAC enabled database running on one node in a cluster. This option adds to the flexibility that Oracle offers for database consolidation while reducing management overhead by providing a standard deployment for Oracle Databases in the enterprise.

External links

• Oracle RAC Documentation
• Oracle Real Application Clusters (official website from Oracle Corporation)
• A Step-By-Step Project Guide for Implementing Oracle RAC

  Oracle 11g Release 2 RAC on Linux Using VMware Server

  Dear friend I am going to share with you my experience on RAC (by using VMware machine)

  One of the biggest obstructions preventing people from setting up test RAC environments is the requirement for shared storage. In a production environment, shared storage is often provided by a SAN or high-end NAS device, but both of these options are very expensive when all you want to do is get some experience installing and using RAC especially for beginner …………………

  Using VMware Server you can run multiple Virtual Machines (VMs) on a single server, allowing you to run both RAC nodes on a single machine. In addition, it allows you to set up shared virtual disks, overcoming the obstacle of expensive shared storage..

  Hardware and Software Requirement for this setup

  The finished system includes the host operating system, two guest operating systems, two sets of Oracle Clusterware, two ASM instances and two Database instances all on a single server.
• Oracle Enterprise Linux 5
• VMware Server
• Oracle 11g Release R2
• Clusterware and DB software

  VMware Server Installation

  Step # 1 just install VMware Server (bcos we are going to install cluster)..It is very simple just by some mouse click on MS Window OS.I hope every body can easily install this.

  1. On the "Connect to Host" dialog, accept the "Local host" option by clicking the "Connect" button.

  2. Click the "Create a new virtual machine" button to start the "New Virtual Machine Wizard". Click the "Next" button on the welcome page.

  3. Select the "Custom" virtual machine configuration and click the "Next" button.

  4. Select the "Linux" guest operating system option, and set the version to "Red Hat Enterprise Linux 4", then click the "Next" button. The RHEL4 option is used because at the time of writing, the current version of VMware server doesn't explicitly support RHEL5, but this setting works fine.

  5. Enter the name "RAC1" and the location

  6. Select the required number of processors and click the "Next" button.(select one)

  7. Uncheck the "Make this virtual machine private" checkbox and click the "Next" button.

  8. Select the amount of memory to associate with the virtual machine.

  9. Accept the "Use bridged networking" option by clicking the "Next" button.

  10. Accept the "LSI Logic" option by clicking the "Next" button.

  11. Select the "Create a new virtual disk" option and click the "Next" button

  12. Accept the "SCSI" option by clicking the "Next" button. It's a virtual disk, so you
  can still use this option even if your physical disk is IDE or SATA.

  13. Set the disk size to "10.0" GB and uncheck the "Allocate all disk space now" option. The latter will make disk access slower, but will save you wasting disk space.

  14. Accept "RAC1.vmdk" as the disk file name and complete the VM creation by clicking the "Finish" button.

  15. On the "VMware Server Console" screen, click the "Edit virtual machine settings" button.

  16. On the "Virtual Machine Settings" screen, highlight the "Floppy 1" drive and click the "- Remove" button. Bcos we have no need for this drive..

  17. Click the "+ Add" button, select a hardware type of "Ethernet Adapter", then click the "Next" button.

  18. Accept the "Bridged" option by clicking the "Finish" button.

  19. Finish by clicking the "OK" button on the Virtual Machine Settings dialog.
  
  
  The virtual machine is now configured so we can start the guest operating system installation.

  Guest Operating System Installation Place the first OEL 5 disk in the CD drive and start the virtual machine by clicking the "Power on this virtual machine" button. The right pane of the VMware Server Console should display a boot loader, then the OEL installation screen.

• · GNOME Desktop Environment
• · Editors
• · Graphical Internet
• · Text-based Internet
• · Development Libraries
• · Development Tools
• · Server Configuration Tools
• · Administration Tools
• · Base
• · System Tools
• · X Window System

  The following information should be set during the installation:

• 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

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

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

  # From Enterprise Linux 5 Disk 1

  cd /media/cdrom/Server

  rpm -Uvh binutils-2.*

  rpm -Uvh elfutils-libelf-0.*

  rpm -Uvh glibc-2.*

  rpm -Uvh glibc-common-2.*

  rpm -Uvh libaio-0.*

  rpm -Uvh libgcc-4.*

  rpm -Uvh libstdc++-4.*

  rpm -Uvh make-3.*

  cd /

  eject

  # From Enterprise Linux 5 Disk 2

  cd /media/cdrom/Server

  rpm -Uvh compat-libstdc++-33*

  rpm -Uvh elfutils-libelf-devel-*

  rpm -Uvh glibc-headers*

  rpm -Uvh glibc-devel-2.*

  rpm -Uvh libgomp*

  rpm -Uvh gcc-4.*

  rpm -Uvh gcc-c++-4.*

  rpm -Uvh libaio-devel-0.*

  rpm -Uvh libstdc++-devel-4.*

  rpm -Uvh unixODBC-2.*

  rpm -Uvh unixODBC-devel-2.*

  cd /

  eject

  # From Enterprise Linux 5 Disk 3

  cd /media/cdrom/Server

  rpm -Uvh sysstat-7.*

  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.

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

  kernel.shmmni = 4096

  # semaphores: semmsl, semmns, semopm, semmni

  kernel.sem = 250 32000 100 128

  net.ipv4.ip_local_port_range = 1024 65000

  net.core.rmem_default=4194304

  net.core.rmem_max=4194304

  net.core.wmem_default=262144

  net.core.wmem_max=262144

  #Virtual

  192.168.2.111   rac1-vip.localdomain    rac1-vip

  192.168.2.112   rac2-vip.localdomain    rac2-vip
  
  

  Run the following command to change the current kernel parameters.

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

  oracle               soft    nproc   2047

  oracle               hard    nproc   16384

  oracle               soft    nofile  1024

  oracle               hard    nofile  65536

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

  session    required     pam_limits.so

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

  SELINUX=disabled

  Create the new groups and users.

  groupadd oinstall

  groupadd dba

  groupadd oper

  groupadd asmadmin

  useradd -u 500 -g oinstall -G dba,oper,asmadmin oracle

  passwd oracle

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

  mkdir -p /u01/crs/oracle/product/11.1.0/crs

  mkdir -p /u01/app/oracle/product/11.1.0/db_1

  chown -R oracle:oinstall /u01

  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_HOSTNAME=rac1.localdomain; export ORACLE_HOSTNAME

  ORACLE_BASE=/u01/app/oracle; export ORACLE_BASE

  ORACLE_HOME=$ORACLE_BASE/product/11.1.0/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 

Install VMware Client Tools

# vmware-config-tools.pl

Create Shared Disks

Shut down the RAC1 virtual machine using the following command.

# shutdown -h now

• Create a directory on the host system to hold the shared virtual disks.

• # mkdir -p /u01/VM/shared

• On the VMware Server Console, click the "Edit virtual machine settings" button. On the "Virtual Machine Settings" screen, click the "+ Add" button.

• Click the "Next" button on the welcome screen, then select the hardware type of "Hard Disk" and click the "Next" button
• Accept the "Create a new virtual disk" option by clicking the "Next" button.
• Accept the "SCSI" option by clicking the "Next" button
• Set the disk size to "10.0" GB and uncheck the "Allocate all disk space now" option, then click the "Next" button.
• Set the disk name to "/u01/VM/shared/ocr.vmdk" and click the "Advanced" button.
• Set the virtual device node to "SCSI 1:1" and the mode to "Independent" and "Persistent", then click the "Finish" button.

• Repeat the previous hard disk creation steps 4 more times, using the following values:

• File Name: /u01/VM/shared/votingdisk.vmdk
  Virtual Device Node: SCSI 1:2
  Mode: Independent and Persistent
• File Name: /u01/VM/shared/asm1.vmdk
  Virtual Device Node: SCSI 1:3
  Mode: Independent and Persistent
• File Name: /u01/VM/shared/asm2.vmdk
  Virtual Device Node: SCSI 1:4
  Mode: Independent and Persistent
• File Name: /u01/VM/shared/asm3.vmdk
  Virtual Device Node: SCSI 1:5
  Mode: Independent and Persistent

• disk.locking = "FALSE"

  diskLib.dataCacheMaxSize = "0"

  diskLib.dataCacheMaxReadAheadSize = "0"

  diskLib.dataCacheMinReadAheadSize = "0"

  diskLib.dataCachePageSize = "4096"

  diskLib.maxUnsyncedWrites = "0"

  scsi1.present = "TRUE"

  scsi1.virtualDev = "lsilogic"

  scsi1.sharedBus = "VIRTUAL"

  scsi1:1.present = "TRUE"

  scsi1:1.mode = "independent-persistent"

  scsi1:1.fileName = "/u01/VM/shared/ocr.vmdk"

  scsi1:1.deviceType = "plainDisk"

  scsi1:1.redo = ""

  scsi1:2.present = "TRUE"

  scsi1:2.mode = "independent-persistent"

  scsi1:2.fileName = "/u01/VM/shared/votingdisk.vmdk"

  scsi1:2.deviceType = "plainDisk"

  scsi1:2.redo = ""

  scsi1:3.present = "TRUE"

  scsi1:3.mode = "independent-persistent"

  scsi1:3.fileName = "/u01/VM/shared/asm1.vmdk"

  scsi1:3.deviceType = "plainDisk"

  scsi1:3.redo = ""

  scsi1:4.present = "TRUE"

  scsi1:4.mode = "independent-persistent"

  scsi1:4.fileName = "/u01/VM/shared/asm2.vmdk"

  scsi1:4.deviceType = "plainDisk"

  scsi1:4.redo = ""

  scsi1:5.present = "TRUE"

  scsi1:5.mode = "independent-persistent"

  scsi1:5.fileName = "/u01/VM/shared/asm3.vmdk"

  scsi1:5.deviceType = "plainDisk"

  scsi1:5.redo = ""

  Start the RAC1 virtual machine by clicking the "Power on this virtual machine" button on the VMware Server Console. When the server has started, log in as the root user so you can partition the disks. The current disks can be seen by issueing the following commands.

  # cd /dev

  # ls sd*

  sda  sda1  sda2  sdb  sdc  sdd  sde  sdf

  #

  Use the "fdisk" command to partition the disks sdb to sdf. The following output shows the expected fdisk output for the sdb disk.

  # fdisk /dev/sdb

  Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel

  Building a new DOS disklabel. Changes will remain in memory only,

  until you decide to write them. After that, of course, the previous

  content won't be recoverable.

  
  
  
  

  The number of cylinders for this disk is set to 1305.

  There is nothing wrong with that, but this is larger than 1024,

  and could in certain setups cause problems with:

  1) software that runs at boot time (e.g., old versions of LILO)

  2) booting and partitioning software from other OSs

     (e.g., DOS FDISK, OS/2 FDISK)

  Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

  Command (m for help): n

  Command action

     e   extended

     p   primary partition (1-4)

  p

  Partition number (1-4): 1

  First cylinder (1-1305, default 1):

  Using default value 1

  Last cylinder or +size or +sizeM or +sizeK (1-1305, default 1305):

  Using default value 1305

  Command (m for help): p

  Disk /dev/sdb: 10.7 GB, 10737418240 bytes

  255 heads, 63 sectors/track, 1305 cylinders

  Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System

  /dev/sdb1               1        1305    10482381   83  Linux

  Command (m for help): w

  The partition table has been altered!

  Calling ioctl() to re-read partition table.

  Syncing disks.

  #

  In each case, the sequence of answers is "n", "p", "1", "Return", "Return", "p" and "w".
  
  Once all the disks are partitioned, the results can be seen by repeating the previous "ls" command.

  # cd /dev

  # ls sd*

  sda  sda1  sda2  sdb  sdb1  sdc  sdc1  sdd  sdd1  sde  sde1  sdf  sdf1

  #

  Add the following commands to the /etc/rc.local file.

  chown oracle:oinstall /dev/sdb1

  chown oracle:oinstall /dev/sdc1

  chown oracle:oinstall /dev/sdd1

  chown oracle:oinstall /dev/sde1

  chown oracle:oinstall /dev/sdf1

  chmod 600 /dev/sdb1

  chmod 600 /dev/sdc1

  chmod 600 /dev/sdd1

  chmod 600 /dev/sde1

  chmod 600 /dev/sdf1

  The shared disks are now configured

  Clone the Virtual Machine