Oracle Database - File System

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File System on Linux

The file system is a storage option for the database files during the installation of a database.

Oracle Database Configuration Assistant creates the database files in a directory on a file system mounted on the computer. Oracle recommends that the file system you choose be separate from the file systems used by the operating system or the Oracle software. The file system that you choose can be any of the following:

  • A file system on a disk that is physically attached to the system

If you are creating a database on basic disks that are not logical volumes or RAID devices, then Oracle recommends that you follow the Optimal Flexible Architecture (OFA) recommendations and distribute the database files over more than one disk.

If you are using multiple disks in an LVM or RAID configuration, then Oracle recommends that you use the stripe and mirror everything (SAME) methodology to increase performance and reliability. Using this methodology, you do not need to specify more than one file system mount point for database storage.

If you choose the Advanced database creation option, then you can also choose to use the Oracle-managed files feature with the new database. If you use this feature, then you must specify only the database object name instead of file names when creating or deleting database files.

Guidelines on Linux

If you choose to place the Oracle Database files on a file system, then use the following guidelines when deciding where to place them:

  • The default path suggested by Oracle Universal Installer for the database file directory is a subdirectory of the Oracle base directory.
  • You can choose either a single file system or more than one file system to store the database files:
    • If you want to use a single file system, then choose a file system on a physical device that is dedicated to the database. For best performance and reliability, choose a RAID device or a logical volume on more than one physical device and implement the stripe-and-mirror-everything (SAME) methodology.
    • If you want to use more than one file system, then choose file systems on separate physical devices that are dedicated to the database. This method enables you to distribute physical input-output operations and create separate control files on different devices for increased reliability. It also enables you to fully implement the OFA guidelines. You can choose the Advanced database creation option to implement this method.
  • If you intend to create a preconfigured database during the installation, then the file system (or file systems) that you choose must have at least 2 GB of free disk space. For production databases, you must estimate the disk space requirement depending on the use that you want to make of the database.
  • For optimum performance, the file systems that you choose should be on physical devices that are used only by the database.
  • The oracle user must have write permissions to create the files in the path that you specify.

Creating Required Installation Directories

You must perform this procedure only if you want to place the Oracle Database or recovery files on a separate file system to the Oracle base directory.

To create directories for the Oracle database, or recovery files on separate file systems to the Oracle base directory:

  • Use the following to determine the free disk space on each mounted file system:
# df -h
  • From the display, identify the file systems that you want to use:
File Type File System Requirements
Database files Choose either:
* A single file system with at least 2 GB of free disk space
* Two or more file systems with at least 2 GB of free disk space in total
Recovery files Choose a file system with at least 2.4 GB of free disk space
  • Note the names of the mount point directories for the file systems that you identified.
  • Enter commands similar to the following to create the recommended subdirectories in each of the mount point directories and set the appropriate owner, group, and permissions on them:
    • Database file directory:
# mkdir /mount_point/oradata
# chown oracle:oinstall /mount_point/oradata
# chmod 775 /mount_point/oradata

The default location for Database file directory is ORACLE_BASE/oradata.

  • Recovery file directory (fast recovery area):
# mkdir /mount_point/recovery_area
# chown oracle:oinstall /mount_point/recovery_area
# chmod 775 /mount_point/recovery_area

The default fast recovery area is ORACLE_BASE/recovery_area. However, Oracle recommends that you keep the fast recovery area on a separate physical disk than that of the database file directory. This will enable you use the fast recovery area to retrieve data if the disk containing oradata is unusable due to any reasons.

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