You must configure certain users, groups, and environment settings used during Oracle Grid Infrastructure for a Cluster and Oracle Real Application Clusters installations.

• Creating Installation Groups and Users for Oracle Grid Infrastructure and Oracle RAC
  To install Oracle Grid Infrastructure and Oracle RAC, you must have an installation user and optionally an Oracle Home User.
• Standard Administration and Job Role Separation User Groups
  Oracle Grid Infrastructure uses various operating system groups.
• Configuring User Accounts
  When installing Oracle Grid Infrastructure for a cluster, you run the installer software as an Administrator user. During installation, you can specify an Oracle Home user.
• Creating Oracle Software Directories
  During installation, you are prompted to provide a path to a home directory to store Oracle Grid Infrastructure software.
• Enabling Intelligent Platform Management Interface (IPMI)
  Intelligent Platform Management Interface (IPMI) provides a set of common interfaces to computer hardware and firmware that system administrators can use to monitor system health and manage the system.