C Configuring Raw Devices for Oracle Real Application Clusters

This appendix provides additional information about configuring raw devices to deploy Real Application Clusters (RAC) using Oracle Database Configuration Assistant (DBCA). You must configure raw devices if you do not use Automatic Storage Management (ASM), or Oracle Cluster File System.

C.1 Raw Devices Required by DBCA for Non-OCFS Environments

If you want to use DBCA to create a database on raw storage, then configure the raw devices, as described in this section. These devices are in addition to the Oracle Cluster Registry (OCR) and voting disk required to install Oracle Clusterware. Create these devices before running Oracle Universal Installer (OUI) to install the Oracle Database 10g software. DBCA cannot create a RAC database unless you have properly configured the following devices:

  • Four raw devices for four tablespace data files

  • At least two raw devices for control files

  • One raw device for each instance for its own tablespace for automatic undo management

  • At least two raw devices for redo log files for each instance

  • One raw device for the server parameter file


    Each instance has its own redo log files, but all instances in a cluster share the control files and data files. In addition, each instance's online redo log files must be readable by all other instances to enable recovery.

C.1.1 Planning Your Raw Device Creation Strategy

Before installing the Oracle Database 10g software with Oracle Real Application Clusters, create enough partitions of specific sizes to support your database, and also leave a few spare partitions of the same size for future expansion. For example, if you have space on your shared disk array, then select a limited set of standard partition sizes for your entire database. Partition sizes of 50 MB, 100 MB, 500 MB, and 1 GB are suitable for most databases. Also, create a few very small and a few very large spare partitions that are (for example) 1 MB and perhaps 5 GB or greater in size. Based on your plans for using each partition, determine the placement of these spare partitions by combining different sizes on one disk, or by segmenting each disk into same-sized partitions.


Ensure that there are spare partitions enables you to perform emergency file relocations or additions if a tablespace data file becomes full.