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Oracle® Database 2 Day + Real Application Clusters Guide
12c Release 1 (12.1)

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2 Preparing Your Cluster

This chapter contains the information that your system administrator and network administrator need to help you, as the DBA, configure two nodes in your cluster. This chapter assumes a basic understanding of the Linux operating system. In some cases, you may need to refer to details in Oracle Grid Infrastructure Installation Guide for your operating system. In addition, you must have these additional privileges have to perform certain tasks in this chapter: root or sudo privileges for UNIX and Linux systems, Administrator privileges on Windows systems.

This chapter includes the following sections:

Verifying System Requirements

Before you begin your installation, check to ensure that your system meets the requirements for Oracle Real Application Clusters (Oracle RAC). The requirements can be grouped into the following categories:

Checking Operating System Certifications

You must ensure that you have a certified combination of the operating system and the Oracle Database software. Refer to My Oracle Support certification, which is located at the following website

https://support.oracle.com

You can find certification information by selecting the Certifications tab. You can also search for support notes that contain instructions on how to locate the Certification information for your platform.

Note:

Oracle Universal Installer verifies that your server and operating system meet the listed requirements. However, you should check the requirements before you start Oracle Universal Installer to ensure your server and operating system meet the requirement. This helps to avoid delays in the software installation process that you might incur if your hardware or software is not certified.

About Hardware Requirements

Each node you make part of your cluster, or Oracle Clusterware and Oracle RAC installation, must satisfy the minimum hardware requirements of the software.

Note:

When you install Oracle software, Oracle Universal Installer (OUI) automatically performs hardware prerequisite checks and notifies you if they are not met.

The minimum hardware requirements are:

  • At least 4 GB of RAM for Oracle Grid Infrastructure for a Cluster installations, including installations where you plan to install Oracle RAC

  • An amount of swap space that is at least equal to the amount of RAM

  • Temporary space (at least 1 GB) available in /tmp

  • A processor type (CPU) that is certified with the release of the Oracle software being installed (64-bit)

  • A minimum of 1024 x 786 display resolution, so that Oracle Universal Installer (OUI) displays correctly

  • All servers in the cluster have the same chip architecture, for example, all 64-bit processors

  • Adequate disk space in the software installation locations to store the Oracle software:

    Note:

    Refer to the Oracle Grid Infrastructure Installation Guide and the Oracle Real Application Clusters Installation Guide for your operating system for the actual disk space requirements. The amount of disk space used by the Oracle software can vary, and might be higher than what is listed in this guide.
    • At least 8 GB of available disk space for the Grid home directory, which includes both the binary files for Oracle Clusterware and Oracle Automatic Storage Management (Oracle ASM)

    • Additional disk space (100 GB is recommended) for the Grid home directory for associated log files and patches.

    • At least 3.5 GB of space for the Oracle base of the Oracle Grid Infrastructure installation owner (Grid user). The Oracle base includes Oracle Clusterware and Oracle ASM log files.

    • At least 5.8 GB of disk space for the Oracle home (the location for the Oracle Database software binaries).

About Shared Storage

An Oracle RAC database is a shared everything database. All data files, control files, redo log files, and the server parameter file (SPFILE) used by the Oracle RAC database must reside on shared storage that is accessible by all the Oracle RAC database instances. The Oracle RAC installation demonstrated in this guide uses Oracle ASM for the shared storage for Oracle Clusterware and Oracle Database files.

Oracle Clusterware achieves superior scalability and high availability by using the following components:

  • Voting disk–Manages cluster membership and arbitrates cluster ownership between the nodes in case of network failures. The voting disk is a file that resides on shared storage. For high availability, Oracle recommends that you have multiple voting disks, and that you have an odd number of voting disks. If you define a single voting disk, then use mirroring at the file system level for redundancy.

  • Oracle Cluster Registry (OCR)–Maintains cluster configuration information and configuration information about any cluster database within the cluster. The OCR contains information such as which database instances run on which nodes and which services run on which databases. The OCR also stores information about processes that Oracle Clusterware controls. The OCR resides on shared storage that is accessible by all the nodes in your cluster. Oracle Clusterware can multiplex, or maintain multiple copies of, the OCR and Oracle recommends that you use this feature to ensure high availability.

Note:

If you choose not to use Oracle ASM for storing your Oracle Clusterware files, then both the voting disks and the OCR must reside on a cluster file system that you configure before you install Oracle Clusterware in the Grid home.

These Oracle Clusterware components require the following disk space on a shared file system:

  • Three Oracle Clusterware Registry (OCR) files, a least 400 MB for each, or 1.2 GB total disk space

  • Three voting disk files, 300 MB each, or 900 MB total disk space

If you are not using Oracle ASM for storing Oracle Clusterware files, then for best performance and protection, you should use multiple disks, each using a different disk controller for voting disk file placement. Ensure that each voting disk is configured so that it does not share any hardware device or have a single point of failure.

Note:

Oracle recommends that you create a Grid Infrastructure Management Repository. This repository is an optional component, but if you do not select this feature during installation, then you lose access to Oracle Database Quality of Service management, Memory Guard, and Cluster Health Monitor. You cannot enable these features after installation except by reinstalling Oracle Grid Infrastructure.

If you choose to create a Grid Infrastructure Management Repository, then additional space may be needed for shared storage. See the chapter on configuring storage in Oracle Grid Infrastructure Installation Guide.

About Network Hardware Requirements

Oracle Clusterware requires that you connect the nodes in the cluster to a private network by way of a private interconnect. The private interconnect is a separate network that you configure between cluster nodes. The interconnect serves as the communication path between nodes in the cluster. This interconnect should be a private interconnect, meaning it is not accessible to nodes that are not members of the cluster.

The interconnect used by Oracle RAC is the same interconnect that Oracle Clusterware uses. Each cluster database instance uses the interconnect for messaging to synchronize the use of shared resources by each instance. Oracle RAC also uses the interconnect to transmit data blocks that are shared between the instances.

When you configure the network for Oracle RAC and Oracle Clusterware, each node in the cluster must meet the following requirements:

  • Each node must have at least two network interface cards (NICs), or network adapters. One adapter is for the public network interface and the other adapter is for the private network interface (the interconnect). Install additional network adapters on a node if that node meets either of the following conditions:

    • Does not have at least two network adapters

    • Has two network interface cards but is using network attached storage (NAS). You should have a separate network adapter for NAS.

    • Has two network cards, but you want to use the Redundant Interconnect Usage feature, which allows multiple network adapters to be accessed as a single adapter. Redundant Interconnect Usage enables load-balancing and high availability across multiple (up to 4) private networks (also known as interconnects).

      See Also:

      Oracle Grid Infrastructure Installation Guide for Linux for more information about the configuration requirements for Redundant Interconnect Usage
  • For easier management, public interface names should be the same for all nodes. If the public interface on one node uses the network adapter eth0, then you should configure eth0 as the public interface on all nodes. Network interface names are case-sensitive.

  • The network adapter for the public interface must support TCP/IP.

  • The network adapter for the private interface must support the user datagram protocol (UDP) using high-speed network adapters and a network switch that supports TCP/IP (Gigabit Ethernet or better).

    Note:

    • UDP is the default interface protocol for Oracle RAC and Oracle Clusterware.

    • You must use a switch for the interconnect. Oracle recommends that you use a dedicated network switch. Token-rings or crossover cables are not supported for the interconnect.

    • Loopback devices are not supported.

  • For the private network, the endpoints of all designated interconnect interfaces must be completely reachable on the network. Every node in the cluster must be able to connect to every private network interface in the cluster.

  • The host name of each node must conform to the RFC 952 standard, which permits alphanumeric characters. Host names using underscores ("_") are not allowed.

About IP Address Requirements

When performing an advanced installation of Oracle Grid Infrastructure for a cluster, you can chose to use Grid Naming Service (GNS) and Dynamic Host Configuration Protocol (DHCP) for virtual IPs (VIPs). GNS uses multicast Domain Name Server (mDNS) to enable the cluster to assign host names and IP addresses dynamically as nodes are added and removed from the cluster, without requiring additional network address configuration in the domain name server (DNS).

You can configure the public network interfaces for cluster nodes to use IPv4, IPv6, or both types of IP addresses. During installation, the nodes can be connected to networks that have both address types, but you cannot configure the VIPs to use both address types during installation. After installation, you can configure cluster member nodes with a mixture of IPv4 and IPv6 addresses. Oracle Grid Infrastructure and Oracle RAC support the standard IPv6 address notations specified by RFC 2732.

This guide documents how to perform a typical installation, which does not use GNS and uses only IPv4 addresses. You must configure the following addresses manually in your corporate DNS:

  • A fixed public IP address for each node

  • A virtual IP address for each node

  • Three single client access name (SCAN) addresses for the cluster

Note:

Oracle Clusterware uses interfaces marked as private as the cluster interconnects. You do not need to specify IP addresses for the interconnect.

During installation a SCAN for the cluster is configured, which is a domain name that resolves to all the SCAN addresses allocated for the cluster. The public IP addresses, SCAN addresses, and VIP addresses must all be on the same subnet. The SCAN must be unique within your network. The SCAN addresses should not respond to ping commands before installation. In a Typical installation, the SCAN is also the name of the cluster, so the SCAN must meet the same requirements as the cluster name and can be no longer than 15 characters.

During installation of the Oracle Grid Infrastructure for a cluster, a listener is created for each of the SCAN addresses. Clients that access the Oracle RAC database should use the SCAN or SCAN address, not the VIP name or address. If an application uses a SCAN to connect to the cluster database, then the network configuration files on the client computer do not have to be modified when nodes are added to or removed from the cluster. The SCAN and its associated IP addresses provide a stable name for clients to use for connections, independent of the nodes that form the cluster. Clients can connect to the cluster database using the easy connect naming method and the SCAN.

See Also:

Verifying Operating System and Software Requirements

Refer to the Oracle Grid Infrastructure Installation Guide and the Oracle Real Application Clusters Installation Guide for your platform for information about specific requirements for your environment.

About Operating System and Software Requirements

The operating system and software requirements might include:

  • The operating system release

  • The kernel version of the operating system

  • Modifying the values for kernel parameters

  • Installed packages, patches, or patch sets

  • Installed compilers and drivers

  • Web browser type and version

  • Additional application software requirements

If you are currently running an operating system release that is not supported by Oracle Database 12c Release 1 (12.1), then you must first upgrade your operating system before installing Oracle Real Application Clusters.

If you are using Oracle Linux as your operating system, then you can use the Oracle Validated RPM system configuration script to configure your system.

About Installation Fixup Scripts

Oracle Universal Installer (OUI) detects when the minimum requirements for an installation are not met, and creates shell scripts, called Fixup scripts, to finish incomplete system configuration steps. If OUI detects an incomplete task, then it generates a Fixup script (runfixup.sh). You can run the script after you click Fix and Check Again.

Fixup scripts do the following:

  • If necessary set, kernel parameters to values required for successful installation, including:

    • Shared memory parameters

    • Open file descriptor and UDP send/receive parameters

  • Create and set permissions on the Oracle Inventory (central inventory) directory.

  • Create or reconfigure primary and secondary group memberships for the installation owner, if necessary, for the Oracle Inventory directory and the operating system privileges groups

  • Set shell limits if necessary to required values.

Checking the Current Operating System Configuration

Instead of waiting for the installation to notify you of an incorrect configuration, you can use the command in this section to manually check the operating system configuration before installation. This helps you determine if additional time will be needed to update the operating system before starting the Oracle Grid Infrastructure installation.

To determine if the operating system requirements for Oracle Linux have been met:

  1. To determine which distribution and version of Linux is installed, enter the one of the following commands at the operating system prompt as the root user:

    # cat /etc/oracle-release
    # cat /etc/redhat-release
    # lsb_release -id
    
  2. To determine which chip architecture each server is using and which version of the software you should install, run the following command at the operating system prompt as the root user:

    # uname -m
    

    This command displays the processor type. For a 64-bit architecture, the output would be "x86_64".

  3. To determine if the required errata level is installed, run the uname command as the root user, as shown in this example:

    # uname -r
    2.6.39-100.7.1.el6uek.x86_64
    

    Like most software, the Linux kernel is updated to fix bugs in the operating system. These kernel updates are referred to as erratum kernels or errata levels.

    The output in the previous example shows that the kernel version is 2.6.39, and the errata level (EL) is 100.7.1.e16uek. Review the required errata level for your distribution. If the errata level is below the required minimum errata level, then install the latest kernel update for your operating system. The kernel updates are available from your operating system vendor.

  4. To ensure there are no operating system issues affecting installation, make sure you have installed all the operating system patch updates and packages that are listed in Oracle Grid Infrastructure Installation Guide for your platform. If you are using Oracle Linux, then you can determine if the required packages, or programs that perform specific functions or calculations, are installed by using the following command as the root user:

    # rpm -q package_name
    

    The variable package_name is the name of the package you are verifying, such as setarch. If a package is not installed, then install it from your Linux distribution media or download the required package version from your Linux vendor's website.

    You can also use either up2date or YUM (Yellow dog Updater Modified) to install packages and their dependencies on some Linux systems. YUM uses repositories to automatically locate and obtain the correct RPM packages for your system.

Preparing the Server

After you have verified that your system meets the basic requirements for installing Oracle RAC, the next step is to configure the server in preparation for installation.

This section describes how to perform the following tasks:

About Operating System Users and Groups

Depending on whether this is the first time Oracle software is being installed on this server, you may have to create operating system groups and users.

The following topics discuss the types of users required for Oracle Clusterware and Oracle RAC:

Required Operating System Users and Groups

To install Oracle Grid Infrastructure for a cluster and Oracle RAC, the operating system groups and users in the following table are required:

Operating System User or Group Description
The Oracle Inventory group for all Oracle software installations (oinstall). The Oracle Inventory group must be the primary group for Oracle software installation owners on Linux and UNIX platforms. Members of the Oracle Inventory group have access to the Oracle Inventory directory. This directory is the central inventory record of all Oracle software installations on a server and the installation logs and trace files from each installation. On Windows systems, this group is created and managed automatically.
An Oracle software owner, or installation user. This is the user account you use when installing the software. If you want to use a single software owner for all installations, then typically the user name is oracle. If you plan to install Oracle Grid Infrastructure for a cluster and Oracle RAC using separate software owners to separate Oracle Grid Infrastructure for a cluster administrative privileges from Oracle Database administrative privileges, then typically you would use grid for Oracle Grid Infrastructure for a cluster owner and oracle for the Oracle RAC owner.
The OSDBA group (typically, dba) for Oracle Database authentication. The OSDBA group is a system privileges group whose members are granted the SYSDBA privilege to administer Oracle Database and the SYSASM privilege to administer Oracle Clusterware and Oracle ASM. To provide fine-grained control of administrative privileges you can create multiple operating system groups as described in "Optional Operating System Users and Groups".

Note:

When installing Oracle RAC on a Microsoft Windows platform:
  • OUI automatically creates the groups used for systsem authenticating access to the Oracle software.

  • The user performing the installation must be an Administrator user.

  • If you specify an Oracle Home user during installation, this user must be a domain user.

On Linux and UNIX systems, if you use one installation owner for both Oracle Grid Infrastructure for a cluster and Oracle RAC, then when you want to perform administration tasks, you must change the value for ORACLE_HOME environment variable to match the instance you want to administer (Oracle ASM, in the Grid home, or a database instance in the Oracle home). To change the ORACLE_HOME environment variable, use a command syntax similar to the following example, where /u01/app/12.1.0/grid is the Oracle Grid Infrastructure for a cluster home:

ORACLE_HOME=/u01/app/12.1.0/grid; export ORACLE_HOME

If you try to administer an instance using SQL*Plus, LSNRCTL, or ASMCMD while ORACLE_HOME is set to an incorrect binary path, then you will encounter errors. The Oracle home path does not affect SRVCTL commands.

On Windows systems, to perform administration tasks, you simply run the appropriate utility for either Oracle Grid Infrastructure or Oracle RAC and ORACLE_HOME is configured automatically.

Separate Operating System Users and Groups for Oracle Software Installations on UNIX and Linux Systems

Instead of using a single operating system user as the owner of every Oracle software installation, you can use multiple users, each owning one or more Oracle software installations. A user created to own only the Oracle Grid Infrastructure for a cluster installation is called the grid user. This user owns both the Oracle Clusterware and Oracle Automatic Storage Management binaries. A user created to own either all Oracle software installations (including Oracle Grid Infrastructure for a cluster), or only Oracle Database software installations, is called the oracle user.

You can also use different users for each Oracle Database software installation. Additionally, you can specify a different OSDBA group for each Oracle Database software installation. By using different operating system groups for authenticating administrative access to each Oracle Database installation, users have SYSDBA privileges for the databases associated with their OSDBA group, rather than for all the databases on the system.

Members of the OSDBA group can also be granted the SYSASM system privilege, which gives them administrative access to Oracle ASM. As described in "Optional Operating System Users and Groups", you can configure a separate operating system group for Oracle ASM authentication to separate users with SYSASM access to the Oracle ASM instances from users with SYSDBA access to the database instances.

If you want to create separate Oracle software owners so you can use separate users and operating system privilege groups for the different Oracle software installations, then note that each of these users must have the Oracle central inventory group (oinstall) as their primary group. Members of this group have the required write privileges to the Oracle Inventory directory.

Note:

The Oracle Grid Infrastructure for a cluster installation can be owned by only one user. You cannot have one user that owns the Oracle Clusterware installed files and a different user that owns the Oracle ASM installed files.

Separate Operating System Users and Groups for Oracle Software Installations on Windows Systems

You create at least one Oracle Installation user (an Administrator user who installs Oracle software) when you install Oracle Grid Infrastructure. You can use this Oracle Installation user or a different Oracle Installation user when installing Oracle Database software.

You should create additional non-privileged Windows user accounts to be used as Oracle Home users during installation. An Oracle Home User is different from an Oracle Installation user. An Oracle Installation user is the user who needs administrative privileges to install Oracle products. An Oracle Home user is a low-privileged Windows User Account specified during installation that runs most of the Windows services required for the Oracle home. Different Oracle homes on a system can share the same Oracle Home user or use different Oracle Home users. You do not need to create any operating system groups because they are created and managed automatically by the Oracle software.

The Oracle Home user can be a Built-in Account or a Windows domain user. The Windows domain user should be a low-privileged, non-administrative account to ensure that the Oracle Database services running under Oracle Home User have only those privileges required to run Oracle products. Create separate Oracle Home users for each Oracle software product to have separate administrative controls for the different Oracle Homes.

If you use different Oracle Home users for each Oracle Database software installation, then you can use the ORA_HOMENAME_DBA group that is associated with each Oracle home to separate SYSDBA privileges for each installation. A member of an ORA_HOMENAME_DBA group can use operating system authentication to log in to only the Oracle Databases that run from the Oracle home with the name HOMENAME. Members of the ORA_DBA group can use operating system authentication to log in to any Oracle database with SYSDBA privileges.

You can also use the Oracle ASM access control feature to enable role separation for Oracle ASM management. In previous releases, this feature was disabled on Windows because all Oracle Database services ran as Local System. For Oracle ASM administration, the new groups ORA_ASMADMIN, ORA_ASMDBA and ORA_ASMOPER are automatically created and populated during Oracle Grid Infrastructure installation.

Optional Operating System Users and Groups

You can use additional users and groups to divide administrative access privileges to the Oracle Grid Infrastructure for a cluster installation from other administrative users and groups associated with other Oracle installations. Separating administrative access is implemented by specifying membership in different operating system groups, and separating installation privileges is implemented by using different installation owners for each Oracle installation.

The optional users and groups you can use are:

  • The Oracle Automatic Storage Management Group, or OSASM group (typically asmadmin for Linux and ORA_ASMADMIN for Windows).

  • The ASM Database Administrator group, or OSDBA for ASM group (typically asmdba for Linux and ORA_ASMDBA for Windows).

  • The OSOPER for Oracle Database group (typically, oper on Linux and ORA_OPER on Windows).

  • The OSOPER for Oracle ASM group (typically asmoper on Linux and ORA_ASMOPER on Windows).

  • The OSBACKUPDBA group for Oracle Database.

  • The OSDGDBA group for Oracle Data Guard.

  • The OSKMDBA group for encryption key management.

See Also:

Configuring Operating System Users and Groups on Linux Systems

In this guide, a single software owner is used for all installations, named oracle. The oracle user belongs to the oinstall and dba operating system groups.

See Also:

Oracle Grid Infrastructure Installation Guide for your operating system for specific instructions

To create one software owner with all operating system-authenticated administration privileges:

  1. Determine the groups that exist on your server by listing the contents of the /etc/group file.

    cat /etc/group
    
  2. If this is the first time Oracle software has been installed on your server, and the Oracle Inventory group does not exist, then create the Oracle Inventory group (oinstall) with a group ID that is currently not in use on all the nodes in your cluster. Enter a command as the root user that is similar to the following:

    # /usr/sbin/groupadd -g 1000 oinstall
    
  3. Create an OSDBA (dba) group with a group ID that is currently not in use on all the nodes in your cluster by entering a command as the root user that is similar to the following:

    # /usr/sbin/groupadd -g 1001 dba
    
  4. If the user that owns the Oracle software (oracle) does not exist on your server, then you must create the user. Select a user ID (UID) that is currently not in use on all the nodes in your cluster. To determine which users have been created on your server, list the contents of the /etc/passwd file using the command:

    cat /etc/passwd
    

    The following command shows how to create the oracle user and the user's home directory (/home/oracle) with the default group as oinstall and the secondary group as dba, using a UID of 1100:

    # useradd -u 1100 –g oinstall -G dba -d /home/oracle -r oracle
    
  5. Set the password for the oracle account using the following command. Replace password with your own password.

    passwd oracle
    
    Changing password for user oracle.
    New UNIX password: password 
    retype new UNIX password: password
    passwd:  all authentication tokens updated successfully.
    
  6. Repeat Step 1 through Step 5 on each node in your cluster.

  7. Verify that the attributes of the user oracle are identical on each node of your cluster:

    id oracle 
    

    The command output should be similar to the following:

    uid=1100(oracle) gid=1000(oinstall) groups=1000(oinstall),1001(dba)
    

Configuring Secure Shell on Linux Systems

To install Oracle software, Secure Shell (SSH) connectivity must be set up between all cluster member nodes. OUI uses the ssh and scp commands during installation to run remote commands on and copy files to the other cluster nodes. You must configure SSH so that these commands do not prompt for a password. SSH is also used by the configuration assistants, Enterprise Manager, and when adding nodes to the cluster.

You can configure SSH from the Oracle Universal Installer (OUI) interface during installation for the user account running the installation. The automatic configuration creates passwordless SSH connectivity between all cluster member nodes.

To enable the script to run, you must remove stty commands from the profiles of any Oracle software installation owners, and remove other security measures that are triggered during a login, and that generate messages to the terminal. These messages, mail checks, and other displays prevent Oracle software installation owners from using the SSH configuration script that is built into the Oracle Universal Installer. If they are not disabled, then SSH must be configured manually before an installation can be run.

On Linux systems, to enable Oracle Universal Installer to use the ssh and scp commands without being prompted for a pass phrase, you must have user equivalency in the cluster. User equivalency exists in a cluster when the following conditions exist on all nodes in the cluster:

  • A given user has the same user name, user ID (UID), and password.

  • A given user belongs to the same groups.

  • A given group has the same group ID (GID).

See Also:

About Configuring the Software Owner's Shell Environment on Linux Systems

On Oracle Linux, you run Oracle Universal Installer (OUI) from the oracle account. OUI obtains information from the environment variables configured for the oracle user. Before running OUI, you must make the following changes to the shell startup file for the software owner of Oracle Grid Infrastructure for a cluster:

  • Set the default file mode creation mask (umask) of the installation user (oracle) to 022 in the shell startup file. Setting the mask to 022 ensures that the user performing the software installation creates files with 644 permissions.

  • Set ulimit settings for file descriptors (nofile) and processes (nproc) for the installation user (oracle).

  • Set the software owner's environment variable DISPLAY environment variables in preparation for the Oracle Grid Infrastructure for a cluster installation.

  • Remove any lines in the file that set values for ORACLE_SID, ORACLE_HOME, or ORACLE_BASE environment variables.

After you have saved your changes, run the shell startup script to configure the environment.

Also, if the /tmp directory has less than 1 GB of available disk space, but you have identified a different, non-shared file system that has at least 1 GB of available space, then you can set the TEMP and TMPDIR environment variables to specify the alternate temporary directory on this file system.

To review your current environment settings, use the env | more command as the oracle user.

Refer to the Oracle Grid Infrastructure Installation Guide for your platform for more information on how to configure the Oracle software owner environment before installation.

Note:

Remove any stty commands from hidden files (such as logon or profile scripts) before you start the installation. On Linux systems, if there are any such files that contain stty commands, then when these files are loaded by the remote shell during installation, OUI indicates an error and stops the installation.

Configuring the Network

Oracle Database 12c Release 1 (12.1) clients connect to the database using a single client access name (SCAN). The SCAN and its associated IP addresses provide a stable name for clients to use for connections, independent of the nodes that form the cluster. A SCAN works by being able to resolve to multiple IP addresses referencing multiple listeners in the cluster that handle public client connections. The installation process creates these listeners, called SCAN listeners.

To configure the network in preparation for installing Oracle Grid Infrastructure for a cluster:

  1. Determine your cluster name. The cluster name should satisfy the following conditions:

    • The cluster name is at least one character long and less than 15 characters long.

    • The cluster name must consist of the same character set used for host names: single-byte alphanumeric characters (a to z, A to Z, and 0 to 9) and hyphens (-).

    • The cluster name is globally unique throughout your host domain

    • If you use third-party vendor clusterware, then Oracle recommends that you use the vendor cluster name.

  2. Determine the public host name and virtual host name for each node in the cluster.

    • For the public host name, use the primary host name of each node. In other words, use the name displayed by the hostname command. This host name can be either the permanent or the virtual host name, for example: racnode1.

    • Determine a virtual host name for each node. A virtual host name is a public node name that Oracle Clusterware uses to reroute client requests sent to the node if the node is down. Oracle recommends that you provide a name in the format <public hostname>-vip, for example: racnode1-vip.

  3. Identify the interface names and associated IP addresses for all network adapters by executing the following command on each node:

    # /sbin/ifconfig
    

    From the output, identify the interface name (such as eth0) and IP address for each network adapter you specify as a public network interface.

    If your operating system supports a graphic user interface (GUI) for modifying the system configuration, then you can also use the following command to start a GUI that you can use to configure the network adapters and /etc/hosts file:

    /usr/bin/system-config-network &
    

    Note:

    When you install Oracle Clusterware and Oracle RAC, you are asked to provide the interface name and IP address for each network adapter.
  4. On each node in the cluster, assign a public IP address with an associated network name to one network adapter. The public name for each node should be registered with your domain name system (DNS). IP addresses on the subnet you identify as private are assigned as private IP addresses for cluster member nodes. You do not have to configure these addresses manually in the /etc/hosts file.

    You can test whether an interconnect interface is reachable using a ping command.

  5. On each node in the cluster, configure a third IP address that serves as a virtual IP address. Use an IP address that meets the following requirements:

    • The virtual IP address and the network name must not be currently in use.

    • The virtual IP address must be on the same subnet as your public IP address.

    The virtual host name for each node should be registered with your DNS.

  6. Define a SCAN that resolves to three IP addresses in your DNS.

  7. When you complete the network configuration, the IP address and network interface configuration should be similar to what is shown in Table 2-1 (your node names and IP addresses might be different):

    Table 2-1 Manual Network Configuration Example

    Identity Home Node Host Node Given Name Type Address Address Assigned By Resolved By

    Node 1 Public

    Node 1

    racnode1

    racnode1Foot 1 

    Public

    192.0.2.101

    Fixed

    DNS

    Node 1 VIP

    Node 1

    Selected by Oracle Clusterware

    racnode1-vip

    Virtual

    192.0.2.104

    Fixed

    DNS, hosts file

    Node 1 Private

    Node 1

    racnode1

    racnode1-priv

    Private

    192.168.0.1

    Fixed

    DNS, hosts file, or none

    Node 2 Public

    Node 2

    racnode2

    racnode2Footref 1

    Public

    192.0.2.102

    Fixed

    DNS

    Node 2 VIP

    Node 2

    Selected by Oracle Clusterware

    racnode2-vip

    Virtual

    192.0.2.105

    Fixed

    DNS, hosts file

    Node 2 Private

    Node 2

    racnode2

    racnode2-priv

    Private

    192.168.0.2

    Fixed

    DNS, hosts file, or none

    SCAN VIP 1

    none

    Selected by Oracle Clusterware

    docrac-scan

    virtual

    192.0.2.201

    Fixed

    DNS

    SCAN VIP 2

    none

    Selected by Oracle Clusterware

    docrac-scan

    virtual

    192.0.2.202

    Fixed

    DNS

    SCAN VIP 3

    none

    Selected by Oracle Clusterware

    docrac-scan

    virtual

    192.0.2.203

    Fixed

    DNS


    Footnote 1 Node host names may resolve to multiple addresses.

    Even if you are using a DNS, Oracle recommends that you add lines to the /etc/hosts file on each node, specifying the public IP addresses. Configure the /etc/hosts file so that it is similar to the following example:

    #eth0 - PUBLIC
    192.0.2.100       racnode1.example.com       racnode1
    192.0.2.101       racnode2.example.com       racnode2
    

    Note:

    Make a note of the addresses you configured in the /etc/hosts file or registered with DNS. When you install Oracle Grid Infrastructure for a cluster and Oracle RAC, you are prompted for the public, virtual IP, and SCAN addresses.

    Oracle strongly recommends that you do not configure SCAN VIP addresses in the hosts file. Use DNS resolution for SCAN VIPs.

    The fully qualified SCAN for the cluster defaults to cluster_name-scan.GNS_subdomain_name, for example docrac-scan.grid.example.com. The short SCAN for the cluster is docrac-scan. Without GNS, and configuring SCAN in DNS directly, then the fully qualified SCAN would be similar to docrac-scan.example.com. You can use any name for the SCAN, if it is unique within your network and conforms to the RFC 952 standard.

  8. If you configured the IP addresses in a DNS server, then, as the root user, change the hosts search order in /etc/nsswitch.conf on all nodes as shown here:

    Old:

    hosts:  files nis dns
    

    New:

    hosts:  dns files nis
    
  9. After modifying the nsswitch.conf file, restart the nscd daemon on each node using the following command:

    # /sbin/service nscd restart
    

After you have completed the installation process, configure clients to use the SCAN to access the cluster. Using the previous example, the clients would use docrac-scan to connect to the cluster.

Verifying the Network Configuration

After you have configured the network, perform verification tests to make sure it is configured properly. If there are problems with the network connection between nodes in the cluster, then the Oracle Clusterware installation fails.

To verify the network configuration on a two-node cluster that is running Oracle Linux:

  1. As the root user, verify the configuration of the public and private networks. Verify that the interfaces are configured on the same network (either private or public) on all nodes in your cluster.

    In this example, eth0 is used for the public network and eth1 is used for the private network on each node.

    # /sbin/ifconfig
     
    eth0      Link encap:Ethernet  HWaddr 00:0E:0C:08:67:A9  
              inet addr: 192.0.2.100   Bcast:192.0.2.255   Mask:255.255.240.0
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:270332689 errors:0 dropped:0 overruns:0 frame:0
              TX packets:112346591 errors:2 dropped:0 overruns:0 carrier:2
              collisions:202 txqueuelen:1000 
              RX bytes:622032739 (593.2 MB)  TX bytes:2846589958 (2714.7 MB)
              Base address:0x2840 Memory:fe7e0000-fe800000 
     
    eth1      Link encap:Ethernet  HWaddr 00:04:23:A6:CD:59  
              inet addr: 10.10.10.11   Bcast: 10.10.10.255   Mask:255.255.240.0   
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:21567028 errors:0 dropped:0 overruns:0 frame:0
              TX packets:15259945 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:4091201649 (3901.6 MB)  TX bytes:377502797 (360.0 MB)
              Base address:0x2800 Memory:fe880000-fe8a0000 
    
  2. As the root user, verify the network configuration by using the ping command to test the connection from each node in your cluster to all the other nodes. For example, as the root user, you might run the following commands on each node:

    # ping -c 3 racnode1.example.com
    # ping -c 3 racnode1
     
    # ping -c 3 racnode2.example.com
    # ping -c 3 racnode2
    

    You should not get a response from the nodes using the ping command for the virtual IPs (racnode1-vip, racnode2-vip) or the SCAN IPs until after Oracle Clusterware is installed and running. If the ping commands for the public addresses fail, then resolve the issue before you proceed.

  3. Ensure that you can access the default gateway with a ping command. To identify the default gateway, use the route command, as described in the Oracle Linux Help utility.

Preparing the Operating System and Software

When you install the Oracle software on your server, Oracle Universal Installer expects the operating system to have specific packages and software applications installed.

This section covers the following topics:

About Setting the Time on All Nodes

Before starting the installation, ensure that the date and time settings on all the cluster nodes are set as closely as possible to the same date and time. A cluster time synchronization mechanism ensures that the internal clocks of all the cluster members are synchronized. For Oracle RAC on Linux, you can use either the Network Time Protocol (NTP) or the Oracle Cluster Time Synchronization Service.

NTP is a protocol designed to synchronize the clocks of servers connected by a network. When using NTP, each server on the network runs client software to periodically make timing requests to one or more servers, referred to as reference NTP servers. The information returned by the timing request is used to adjust the server's clock. All the nodes in your cluster should use the same reference NTP server.

Note:

If you use NTP, then you must configure it using the -x flag.

If you do not configure NTP, then Oracle configures and uses the Cluster Time Synchronization Service (CTSS). CTSS can also be used to synchronize the internal clocks of all the members in the cluster. CTSS keeps the member nodes of the cluster synchronized. CTSS designates the first node in the cluster as the master and then synchronizes all other nodes in the cluster to have the same time as the master node. CTSS does not use any external clock for synchronization.

Note:

Using NTP or CTSS does not protect your system against human error resulting from a change in the system time for a node.

About Configuring Kernel Parameters

OUI checks the current settings for various kernel parameters to ensure they meet the minimum requirements for deploying Oracle RAC. For production database systems, Oracle recommends that you tune the settings to optimize the performance of your particular system.

Note:

If you find parameter settings or shell limit values on your system that are greater than the values mentioned by OUI, then do not modify the parameter setting.

About Performing Platform-Specific Configuration Tasks

You may be required to perform special configuration steps that are specific to the operating system on which you are installing Oracle RAC, or for the components used with your cluster. The following list provides examples of operating-specific installation tasks:

  • Configure the use of Huge Pages on SUSE Linux, Red Hat Enterprise Linux, or Oracle Linux.

  • Set shell limits for the oracle user on Red Hat Linux or Oracle Linux systems to increase the number of files and processes available to Oracle Clusterware and Oracle RAC.

  • Create X library symbolic links on HP-UX.

  • Configure network tuning parameters on AIX Based Systems.

Configuring Installation Directories and Shared Storage

Oracle RAC requires access to a shared file system for storing Oracle Clusterware files. You must also determine where the Oracle software and database files will be installed.

This section describes the storage configuration tasks that you must complete before you start Oracle Universal Installer. It includes information about the following topics:

Note:

Additional configuration is required to use the Oracle Automatic Storage Management library Driver (ASMLIB) with third party vendor multipath disks. Refer to Oracle Grid Infrastructure Installation Guide for your operating system for more details about these requirements.

Locating the Oracle Inventory Directory

The Oracle Inventory (oraInventory) directory is the central inventory record of all Oracle software installations on a server. The oraInventory directory contains the following:

  • A registry of the Oracle home directories (Oracle Grid Infrastructure for a cluster and Oracle Database) on the system

  • Installation logs and trace files from installations of Oracle software. These files are also copied to the respective Oracle homes for future reference

OUI creates the oraInventory directory during installation. By default, the Oracle Inventory directory is not installed under the Oracle Base directory. This is because all Oracle software installations share a common Oracle Inventory, so there is only one Oracle Inventory for all users, whereas each user that performs a software installation can use a separate Oracle base directory.

If you have an existing Oracle Inventory, then ensure that you use the same Oracle Inventory for all Oracle software installations, and ensure that all Oracle software users you intend to use for installation have permissions to write to this directory.

To determine if you have an Oracle central inventory directory (oraInventory) on your system:

  1. Run the following command to check for an existing Oracle Inventory directory:

    # more /etc/oraInst.loc
    
  2. If the oraInst.loc file exists, then the output from this command is similar to the following:

    inventory_loc=/u01/app/oraInventory
    inst_group=oinstall
    

    In the previous output example:

    • The inventory_loc group shows the location of the Oracle Inventory.

    • The inst_group parameter shows the name of the Oracle Inventory group (in this example, oinstall).

  3. If the Oracle Inventory directory does not exist, then the command returns an error message indicating that the file or directory does not exist.

    If the Oracle Inventory directory does not exist, then you do not have to create one before installing the Oracle software.

Creating the Oracle Grid Infrastructure for a Cluster Home Directory

During installation, you are prompted to provide a path to a home directory in which to place the software for Oracle Grid Infrastructure for a cluster. OUI installs Oracle Clusterware and Oracle ASM into a directory referred to as Grid_home. Ensure that the directory path you provide meets the following requirements:

  • It should be created in a path outside existing Oracle homes.

  • It should not be located in a user home directory.

  • It should be created either as a subdirectory in a path where all files can be owned by root, or in a unique path.

  • If you create the path before installation, then it should be owned by the installation owner of Oracle Grid Infrastructure for a cluster (oracle or grid), and set to 775 permissions.

Before you start the installation, you must have sufficient disk space on a file system for the Oracle Grid Infrastructure for a cluster directory. The file system that you use for the Grid home directory must have at least 4.5 GB of available disk space.

The path to the Grid home directory must be the same on all nodes. As the root user, you should create a path compliant with Oracle Optimal Flexible Architecture (OFA) guidelines, so that OUI can select that directory during installation.

To create the Grid home directory:

Log in to the operating system as the root user, then enter the following commands, where oracle is the name of the user that will install the Oracle Grid Infrastructure software:

# mkdir -p /u01/app/12.1.0/grid
# chown -R oracle:oinstall /u01/app/12.1.0/grid

Note:

On Linux and UNIX systems, you must ensure the Grid home directory is not a subdirectory of the Oracle base directory. Installing Oracle Clusterware in an Oracle base directory causes installation errors.

Creating the Oracle Base Directory

Oracle Universal Installer (OUI) creates the Oracle base directory for you in the location you specify. This directory is owned by the user performing the installation. The Oracle base directory (ORACLE_BASE) helps to facilitate the organization of Oracle installations, and helps to ensure that installations of multiple databases maintain an Optimal Flexible Architecture (OFA) configuration. OFA guidelines recommend that you use a path similar to the following for the Oracle base directory:

/mount_point/app/user

In the preceding path example, the variable mount_point is the mount point directory for the file system where you intend to install the Oracle software and user is the Oracle software owner (typically oracle). For OUI to recognize the path as an Oracle software path, it must be in the form u0[1-9]/app, for example, /u01/app.

The path to the Oracle base directory must be the same on all nodes. The permissions on the Oracle base directory should be at least 750.

Example: Creating an Oracle Base Directory

Before installing any Oracle software, you must configure an Oracle base directory, OUI uses the Oracle base directory to determine the location of the Oracle Inventory directory, and also for installing Oracle RAC.

Assume you have determined that the file system mounted as /u01 has sufficient room for both the Oracle Grid Infrastructure for a cluster and Oracle RAC software. You have decided to make the /u01/app/oracle/ directory the Oracle base directory. The user installing all the Oracle software is the oracle user.

To create the Oracle base directory:

  1. Log in as the root user.

  2. Use the mkdir command to create the path to the Oracle base directory.

    # mkdir -p /u01/app/oracle/
    
  3. Change the ownership of the Oracle base path to the Oracle software owner, oracle.

    # chown -R oracle:oinstall /u01/app/oracle/
    
  4. Change the permissions on the Oracle base directory to 775.

    # chmod -R 775 /u01/app/oracle/
    

About the Oracle Home Directory

The Oracle home directory is the location in which the Oracle RAC software is installed. You can use an Oracle home directory created in the local file system, for example, /u01/app/oracle/product/12.1.0/dbhome_1. The same directory must exist on every node in the cluster. You do not have to create these directories before installation. By default, the installer suggests a subdirectory of the Oracle base directory for the Oracle home.

You can also use a shared Oracle home. The location of the shared Oracle home can be on network storage, or a supported cluster file system such as Oracle Automatic Storage Management Cluster File System (Oracle ACFS). For more information about Oracle ACFS, see Oracle Automatic Storage Management Administrator's Guide.

If you use the local file system for the Oracle home directory, and you want to install a different release of Oracle RAC or Oracle Database on the same server, then you must use a separate Oracle home directory for each software installation. Multiple releases of the same product or different products can run from different Oracle homes concurrently. Products installed in one Oracle home do not conflict or interact with products installed in another Oracle home.

Using different Oracle homes for your installed software enables you to perform maintenance operations on the Oracle software in one home without effecting the software in another Oracle home. However, it also increases your software maintenance costs, because each Oracle home must be upgraded or patched separately.

Configuring Shared Storage

Each node in a cluster requires external shared disks for storing the Oracle Clusterware (Oracle Cluster Registry and voting disk) files, and Oracle Database files. The supported types of shared storage depend upon the platform you are using, for example:

  • Oracle Automatic Storage Management (strongly recommended)

  • A supported cluster file system, such as OCFS2 for Linux, or General Parallel File System (GPFS) on IBM platforms

  • Network file system (NFS), which is not supported on Linux on POWER or on IBM zSeries Based Linux

  • (Upgrades only) Shared disk partitions consisting of block devices. Block devices are disk partitions that are not mounted using the Linux file system. Oracle Clusterware and Oracle RAC write to these partitions directly.

    Note:

    You cannot use OUI to install Oracle Clusterware files on block or raw devices. You cannot put Oracle Clusterware binaries and files on Oracle Automatic Storage Management Cluster File System (Oracle ACFS).

If you decide to use OCFS2 to store the Oracle Clusterware files, then you must use the proper version of OCFS2 for your operating system version. OCFS2 works with Oracle Linux and Red Hat Linux kernel version 2.6

For all installations, you must choose the storage option to use for Oracle Clusterware files and Oracle Database files. The examples in this guide use Oracle ASM to store the Oracle Clusterware and Oracle Database files. The Oracle Grid Infrastructure for a cluster and Oracle RAC software is installed on disks local to each node, not on a shared file system.

This guide discusses two different methods of configuring the shared disks for use with Oracle ASM:

Note:

For the most up-to-date information about supported storage options for Oracle RAC installations, refer to the Certifications pages on My Oracle Support at:

https://support.oracle.com

Configuring Files on an NAS Device for Use with Oracle ASM

To use an NFS file system, it must be on a certified NAS device. If you have a certified network attached storage (NAS) device, then you can create zero-padded files in an NFS mounted directory and use those files as disk devices in an Oracle ASM disk group.

To ensure high availability of Oracle Clusterware files on Oracle ASM, you must have at least 2 GB of disk space for Oracle Clusterware files in three separate failure groups, with at least three physical disks. Each disk must have at least 1 GB of capacity to ensure that there is sufficient space to create Oracle Clusterware files.

Use the following guidelines when identifying appropriate disk devices:

  • All of the devices in an Oracle Automatic Storage Management disk group should be the same size and have the same performance characteristics.

  • A disk group should not contain multiple partitions on a single physical disk device.

  • Using logical volumes as a device in an Oracle Automatic Storage Management disk group is not supported with Oracle RAC.

  • The user account with which you perform the installation (oracle) must have write permissions to create the files in the path that you specify.

To configure NAS device files for creating disk groups:

  1. Add and configure access to the disks to the NAS device. Make sure each cluster node has been granted access to all the disks used by Oracle Grid Infrastructure for a cluster and Oracle Database software.

    Refer to your NAS device documentation for more information about completing this step.

  2. On a cluster node, log in as the root user (or use sudo for the following steps).

  3. Configure access to the disks on the NAS devices. The process for completing this step can vary depending on the type of disks and the type of NAS service.

    One example of the configuration process is shown here. The first step is to create a mount point directory on the local system:

    # mkdir -p /mnt/oracleasm
    
  4. To ensure that the NFS file system is mounted when the system restarts, add an entry for the file system in the mount file /etc/fstab.

    For more information about editing the mount file for the operating system, refer to the Linux man pages. For more information about recommended mount options, refer to Oracle Grid Infrastructure Installation Guide for your platform.

  5. Enter a command similar to the following to mount the NFS file system on the local system, where host is the host name or IP address of the file server, and pathname is the location of the storage within NFS (for example, /public):

    # mount <host>:<pathname> /mnt/oracleasm
    
  6. Choose a name for the disk group to create, for example, nfsdg.

  7. Create a directory for the files on the NFS file system, using the disk group name as the directory name, for example:

    # mkdir /mnt/oracleasm/nfsdg
    
  8. Use commands similar to the following to create the required number of zero-padded files in this directory:

    # dd if=/dev/zero of=/mnt/oracleasm/nfsdg/disk1 bs=1024k count=1000
    

    This example creates a 1 GB file named disk1 on the NFS file system. You must create one, two, or three files respectively to create an external, normal, or high redundancy disk group.

  9. Enter the following commands to change the owner, group, and permissions on the directory and files that you created:

    # chown -R oracle:dba /mnt/oracleasm
    # chmod -R 660 /mnt/oracleasm
    
  10. When installing Oracle RAC, if you choose to create an Oracle ASM disk group, then you must change the disk discovery path to specify a regular expression that matches the file names you created, for example, /mnt/oracleasm/nfsdg/*.

Using ASMLIB to Mark the Shared Disks as Candidate Disks

Another option for configuring shared disks is to use the ASMLIB utility. If you configure a shared disk to be mounted automatically when the server restarts, then, unless you have configured special files for device persistence, a disk that appeared as /dev/sdg before the system shutdown can appear as /dev/sdh after the system is restarted.

If you use ASMLIB to configure the shared disks, then when you restart the node:

  • The disk device names do not change

  • The ownership and group membership for these disk devices remains the same

  • You can copy the disk configuration implemented by Oracle ASM to other nodes in the cluster by running a simple command

Note:

If you followed the instructions in the section "Configuring Files on an NAS Device for Use with Oracle ASM" to configure your shared storage, then you do not have to perform the tasks in this section.

The following sections describe how to install and configure ASMLIB, and how to use ASMLIB to configure your shared disk devices:

See Also:

If you choose not to use ASMLIB, then see "Configuring Disk Device Persistence"

Installing ASMLIB

The ASMLIB software for various Linux platforms is available from the Oracle Technology Network. Select the link for your platform on the ASMLIB download page at:

http://www.oracle.com/technetwork/topics/linux/asmlib/index-101839.html

You should see four to six packages for your Linux platform. The oracleasmlib package provides the actual Oracle ASM library. The oracleasm-support package provides the utilities used to get the Oracle ASM driver up and running. Both of these packages must be installed.

The remaining packages provide the kernel driver for the Oracle ASM library. Each package provides the driver for a different kernel. You must install the appropriate package for the kernel you run. Use the uname -r command to determine the version of the kernel on your server. The oracleasm kernel driver package has that version string in its name. For example, if you run Red Hat Enterprise Linux 4 AS, and the kernel you are using is the 2.6.9-55.0.12.ELsmp kernel, then you would choose the oracleasm-2.6.9-55.0.12.ELsmp-2.0.3-1.x86_64.rpm package.

Note:

The Oracle ASMLIB kernel driver (oracleasm) is included in the Unbreakable Enterprise Kernel for Oracle Linux. You do not have to installany driver packages when using this kernel. You must still install the oracleasm-support and oracleasmlib packages.

To install the ASMLIB software packages:

  1. Download the ASMLIB packages to each node in your cluster.

  2. Change to the directory where the package files were downloaded.

  3. As the root user, use the rpm command to install the packages. For example:

    # rpm -Uvh oracleasm-support-2.1.3-1.el4.x86_64.rpm
    # rpm -Uvh oracleasmlib-2.0.4-1.el4.x86_64.rpm
    # rpm -Uvh oracleasm-2.6.9-55.0.12.ELsmp-2.0.3-1.x86_64.rpm
    

    After you have completed these commands, ASMLIB is installed on the system.

  4. Repeat steps 2 and 3 on each node in your cluster.

Configuring ASMLIB

After the ASMLIB software is installed, a few steps have to be taken by the system administrator to make the Oracle ASM driver available. The Oracle ASM driver must be loaded, and the driver file system must be mounted. This is taken care of by the initialization script, /usr/sbin/oracleasm.

To configure the ASMLIB software after installation:

  1. As the root user, run the following command:

    # /usr/sbin/oracleasm configure -I
    

    The script prompts you for the default user and group to own the Oracle ASM driver access point. Specify the Oracle Database software owner (oracle) and the OSDBA group (dba).

    The script also prompts you to specify whether you want to start the ASMLIB driver when the node is started and whether you want to scan for presence of any Oracle Automatic Storage Management disks when the node is started. Answer yes for both of these questions.

  2. Repeat step 1 on each node in your cluster.

Using ASMLIB to Create Oracle ASM Disks

Every disk that is used in an Oracle ASM disk group must be accessible on each node. After you make the physical disk available to each node, you can then mark the disk device as an Oracle ASM disk. The /usr/sbin/oracleasm script is used for this task.

If the target disk device supports partitioning, then you must first create a single partition that encompasses the entire disk. If the target disk device does not support partitioning, then you do not have to create a partition on the disk.

To create Oracle ASM disks using ASMLIB:

  1. As the root user, use oracleasm to create Oracle ASM disks using the following syntax:

    # /usr/sbin/oracleasm createdisk disk_name device_partition_name
    

    In this command, disk_name is the name you choose for the Oracle ASM disk. The name you choose must contain only ASCII capital letters, numbers, or underscores, and the disk name must start with a letter, for example, DISK1 or VOL1, or RAC_FILE1. The name of the disk partition to mark as an Oracle ASM disk is the device_partition_name. For example:

    # /usr/sbin/oracleasm createdisk DISK1 /dev/sdb1
    

    If you must unmark a disk that was used in a createdisk command, then you can use the following syntax:

    # /usr/sbin/oracleasm deletedisk disk_name
    
  2. Repeat step 1 for each disk that Oracle ASM uses.

  3. After you have created all the Oracle ASM disks for your cluster, use the listdisks command to verify their availability:

    # /usr/sbin/oracleasm listdisks
    DISK1
    DISK2
    DISK3
    
  4. On all the other nodes in the cluster, use the scandisks command to view the newly created Oracle ASM disks. You do not have to create the Oracle ASM disks on each node, only on one node in the cluster.

    # /usr/sbin/oracleasm scandisks
    Scanning system for ASM disks                              [  OK  ]
    
    
  5. After scanning for Oracle ASM disks, display the available Oracle ASM disks on each node to verify their availability:

    # /usr/sbin/oracleasm listdisks
    DISK1
    DISK2
    DISK3
    

Note:

At this point, you should restart each node on which you are installing Oracle Grid Infrastructure for a cluster. After the node has restarted, view the configured shared storage on each node. This helps to ensure that the system configuration is complete and persists across node shutdowns.

Configuring Disk Device Persistence

By default, the Linux 2.6 kernel device file naming scheme udev dynamically creates device file names when the server is started, and assigns ownership of them to root. If udev applies default settings, then it changes device file names and owners for voting disks or Oracle Cluster Registry partitions, corrupting them when the server is restarted. For example, a voting disk on a device named /dev/sdd owned by the user grid may be on a device named /dev/sdf owned by root after restarting the server.

If you use ASMLIB, then you do not have to ensure permissions and device path persistency in udev. If you do not use ASMLIB, then you must create a custom rules file for the shared disks mounted on each node. When udev is started, it sequentially carries out rules (configuration directives) defined in rules files. These files are in the path /etc/udev/rules.d/. Rules files are read in lexical order. For example, rules in the file 10-wacom.rules are parsed and carried out before rules in the rules file 90-ib.rules.

Where rules files describe the same devices, on Asianux, Red Hat, and Oracle Linux, the last file read is the one that is applied. On SUSE 2.6 kernels, the first file read is the one that is applied.

To configure a rules file for disk devices, see the chapter on configuring storage in Oracle Grid Infrastructure Installation Guide for your platform.