Oracle 11.2 RAC (Real Application Clusters) is an advanced feature of Oracle databases that allows multiple instances to share a single physical database, ensuring high availability and load balancing. Setting up Oracle 11.2 RAC on Linux 5 requires several key steps, including system configuration, user and permission management, Network Time Protocol (NTP) configuration, resource limit adjustments, and kernel parameter optimization. Below is a structured breakdown of these steps:

  1. Memory Requirements: To maintain stable operation, each host must have at least 1.5GB of memory. This baseline ensures that the Oracle database instance functions efficiently, especially in a cluster environment where additional resources handle cluster communication and failover.

  2. User and Group Creation: Before deploying RAC, create dedicated users and groups. We create two groups: oinstall and dba, and two users: grid and oracle. The grid user manages Grid Infrastructure, while oracle is the database instance owner. Proper user and permission settings are essential for security and operational accuracy.

  3. Installation Directory Creation: Each RAC node requires directories for Oracle software, Grid Infrastructure, and Cluster Resource Software (CRS). For example, /u01/app/11.2.0/grid and /u01/app/oracle are designated for Grid Infrastructure and database instances, with grid and oracle as respective owners, and oinstall as the group.

  4. NTP Service Configuration: Synchronizing time across all cluster nodes is crucial since database operations rely on precise timestamps. Edit /etc/ntp.conf on RAC1 to set restrictions, and use the ntpdate command with cron jobs on RAC2 for regular time updates. Start NTP on RAC1, and set up a scheduled task on RAC2 to ensure consistency.

  5. System Limits Adjustment: Configure /etc/security/limits.conf for oracle and grid users, setting soft and hard limits, including maximum open processes (nproc) and file descriptors (nofile). These adjustments boost Oracle RAC's performance and concurrency.

  6. Kernel Parameter Optimization: Optimize system kernel parameters within /etc/sysctl.conf, ensuring efficient utilization of resources and enhancing database performance.