Oracle RAC 19c Masterclass – Part 3

Oracle Grid Infrastructure 19c Installation Explained: From Planning to a Successful Cluster

Installing Oracle Grid Infrastructure (GI) is one of the most important steps in building a stable Oracle RAC environment. While the installation wizard is straightforward, a successful deployment depends on proper planning long before gridSetup.sh is executed.

Many installation failures are not caused by Oracle software itself, but by issues such as incorrect DNS entries, inconsistent user IDs, shared storage problems, or network configuration errors.

In this article, we’ll walk through the complete installation process, explain the purpose of each step, and highlight the most common pitfalls encountered in production.

What is Oracle Grid Infrastructure?

Oracle Grid Infrastructure provides the software required to run an Oracle RAC cluster.

It includes:

• Oracle Clusterware
• Oracle ASM
• Cluster Ready Services (CRS)
• Cluster Synchronization Services (CSS)
• Oracle High Availability Services (OHAS)
• Cluster resource management

Grid Infrastructure must be installed before the Oracle RAC database software.

Typical RAC Architecture

A two-node RAC environment might look like this:

                    +----------------------+
                    |      DNS / GNS       |
                    +----------+-----------+
                               |
                     Public Network
                               |
          +--------------------+--------------------+
          |                                         |
     +---------+                               +---------+
     | Node 1  |                               | Node 2  |
     +---------+                               +---------+
     | Grid GI |                               | Grid GI |
     | ASM     |                               | ASM     |
     +---------+                               +---------+
           \                                       /
            \                                     /
             +-----------------------------------+
             |        Shared ASM Disks           |
             | OCR | Voting | DATA | FRA         |
             +-----------------------------------+

Installation Prerequisites

Before starting the installation, verify the following:

Operating System

Both nodes should:

• Run the same Linux distribution and version.
• Have identical kernel versions (recommended).
• Be fully patched.

Example:

cat /etc/os-release
uname -r

User and Group Configuration

The grid user must exist on every node.

Example:

grid
oracle

Typical groups:

oinstall
dba
asmadmin
asmdba
asmoper
oper

Verify that:

• User IDs (UID)
• Group IDs (GID)

are identical on every node.

Example:

id grid
id oracle

Configure Hostname Resolution

Oracle recommends using DNS for production environments.

Verify name resolution:

nslookup racnode1
nslookup racnode2
nslookup rac-scan

Verify reverse lookup:

nslookup 192.168.10.101

Incorrect DNS configuration is one of the most common causes of Grid installation failures.

Configure Network Interfaces

Each node typically requires:

Network	Purpose
Public	Client access
Private	RAC interconnect
VIP	Virtual IP
SCAN	Client redirection

Example:

Node1 Public : 192.168.10.101

Node1 VIP    : 192.168.10.111

Private      : 10.10.10.1

SCAN         : 192.168.10.120

Verify interfaces:

ip addr

Shared Storage Preparation

Oracle ASM requires shared disks visible from every node.

Typical disk groups:

Disk Group	Purpose
OCR	OCR + Voting Files
DATA	Database files
FRA	Fast Recovery Area

Example:

/dev/oracleasm/disks/OCR01
/dev/oracleasm/disks/DATA01
/dev/oracleasm/disks/FRA01

Verify visibility:

oracleasm listdisks

or with ASM Filter Driver (ASMFD):

asmcmd afd_lsdsk

Verify Time Synchronization

Cluster nodes must maintain consistent time.

Example:

timedatectl

or

chronyc tracking

Significant time differences can affect cluster stability.

Validate the Environment

Oracle provides the Cluster Verification Utility (CVU).

Example:

cluvfy stage -pre crsinst -n racnode1,racnode2 -verbose

CVU checks:

• Network configuration
• Shared storage
• User permissions
• Required packages
• Kernel parameters
• SSH equivalence

Resolve all critical issues before proceeding.

Configure Passwordless SSH

The grid user must connect to every node without a password.

Generate a key:

ssh-keygen -t rsa

Copy the key:

ssh-copy-id grid@racnode2

Verify:

ssh racnode2 hostname

If a password is requested, SSH configuration is incomplete.

Launch the Installer

Start the installation:

./gridSetup.sh

The installer guides you through several configuration screens.

Step 1 – Select Installation Option

Choose:

Configure Oracle Grid Infrastructure for a New Cluster

Step 2 – Cluster Name

Example:

Cluster Name

RAC19C

Add every node to the cluster.

Example:

racnode1

racnode2

Step 3 – SCAN Configuration

Example:

SCAN Name

rac-scan.oranux.com.tn

Port

1521

Oracle verifies that SCAN resolves to three IP addresses (recommended for production).

Step 4 – Network Configuration

Assign interfaces.

Example:

eth0

Public

eth1

Private

Oracle automatically classifies the interfaces, but verify the assignments before continuing.

Step 5 – ASM Configuration

Choose:

Configure Oracle ASM

Create the first disk group.

Example:

+OCR

Redundancy:

• External
• Normal
• High

For most production environments, Normal Redundancy is commonly used, depending on the underlying storage architecture.

Step 6 – Management Repository

For small environments:

Do not configure GIMR

For larger deployments, evaluate whether the Grid Infrastructure Management Repository (GIMR) is required.

Step 7 – Operating System Groups

Assign the appropriate groups:

ASMADMIN

ASMDBA

ASMOPER

Ensure they match your organization’s standards.

Step 8 – Root Scripts

After the software is copied, execute the root scripts on each node.

Example:

/u01/app/19.0.0/grid/root.sh

Run them in the order specified by the installer.

The root script performs tasks such as:

• Configuring OHAS
• Starting CSSD
• Initializing CRSD
• Creating OCR and Voting Files
• Registering cluster resources

Verify the Installation

Check the Clusterware stack:

crsctl check cluster

Example:

node1

CRS-4537:
Cluster Ready Services is online

node2

CRS-4537:
Cluster Ready Services is online

Verify resources:

crsctl stat res -t

Expected resources include:

ora.asm

ora.DATA.dg

ora.LISTENER.lsnr

ora.scan1.vip

ora.scan2.vip

ora.scan3.vip

Verify ASM:

asmcmd lsdg

Example:

State    Type

MOUNTED  NORMAL

Useful Post-Installation Commands

Cluster status:

olsnodes -n

Node applications:

srvctl status nodeapps

ASM:

srvctl status asm

Listeners:

srvctl status listener

SCAN listeners:

srvctl status scan_listener

Disk groups:

srvctl status diskgroup

These commands provide a quick overview of the cluster after installation.

Common Installation Problems

DNS Resolution Issues

Symptoms:

• SCAN validation fails.
• Node discovery errors.

Verify:

nslookup
host
ping

Shared Disks Not Visible

Symptoms:

• ASM disks not detected.

Verify:

oracleasm listdisks

or

asmcmd afd_lsdsk

SSH Configuration Problems

Symptoms:

• Remote execution failures.

Verify:

ssh racnode2 date

Incorrect User IDs

Symptoms:

• Permission errors.
• Inventory issues.

Verify:

id grid
id oracle

on every node.

Private Network Misconfiguration

Symptoms:

• Cluster Verification Utility failures.
• Node communication problems.

Verify:

oifcfg getif

Ensure the private interconnect is correctly identified.

Best Practices

• Validate the environment with cluvfy before installation.
• Use DNS rather than /etc/hosts in production.
• Use redundant private interconnects.
• Store OCR and Voting Files in redundant ASM disk groups.
• Document all hostnames, IP addresses, and storage mappings.
• Apply the latest supported Grid Infrastructure Release Update after installation.

DBA Tip

The most successful Grid Infrastructure installations begin well before the installer is launched.

In many production deployments, the installation itself completes in less than an hour because the preparation has already been thoroughly validated.

Before running gridSetup.sh, make it a habit to verify:

• DNS resolution
• Shared storage visibility
• SSH equivalence
• Network interfaces
• Time synchronization
• cluvfy results

If all of these checks pass, the installation is usually straightforward. If one of them fails, the installer is often only revealing a problem that already existed.

In RAC deployments, preparation determines success. The installer simply confirms whether that preparation was done correctly.

Conclusion

Installing Oracle Grid Infrastructure is much more than copying software to a server. It establishes the cluster foundation on which Oracle RAC depends.

A successful installation begins with careful planning, validated prerequisites, consistent networking, properly configured shared storage, and thorough pre-installation verification. Once Grid Infrastructure is in place, Clusterware and ASM provide the resilient platform required for Oracle RAC databases.