Use the DBMS_FS package to manage the file systems. Use the procedures in this package to create, mount, unmount and destroy a file system in the Oracle Database.

Multiple PDBs can submit these jobs in parallel. The requests are executed in parallel by different worker threads. You can obtain the status of the operations by querying V$OFS_THREADS. OFSD manages the threads. It creates new worker threads, when the number of current worker threads are less than the value of the OFS_THREADS parameter.

BEGIN
 DBMS_FS.MAKE_ORACLE_FS (
  fstype           => 'dbfs',
  fsname           => 'dbfs_fs1',
  mount_options    => 'TABLESPACE=dbfs_fs1_tbspc');
END;
/
BEGIN
 DBMS_FS.MOUNT_ORACLE_FS (
  fstype           => 'dbfs',                              
  fsname           => 'dbfs_fs1',                              
  mount_point      => '/oracle/dbfs/testfs',                              
  mount_options    => 'default_permissions, allow_other'); 
END;
/
/************** Now you can access the file system. All the FS operations go here ***************/

BEGIN
 DBMS_FS.UNMOUNT_ORACLE_FS (
  fsname           => 'dbfs_fs1',                              
  mount_point      => '/oracle/dbfs/testfs',
  unmount_options    => 'force'); 
END;
/
BEGIN
 DBMS_FS.DESTROY_ORACLE_FS (
  fstype           => 'dbfs',
  fsname           => 'dbfs_fs1');
END;
/

The views that support OFS operations start with V$OFS.

OFSD exposes the database file system through FUSE. Before using OFSD to mount the database file systems, you must install and configure the FUSE module.

1. Set read and execute permissions for an Oracle user to use the FUSE executable file, fusermount.

   sudo chmod o+rx /usr/bin/fusermount

   Use the fusermount file to mount and unmount the FUSE user mode file systems.
2. Set the setuid bit on the fusermount file to permit an Oracle user to mount file systems.

   sudo chmod u+s /usr/bin/fusermount

3. Permit other users to access the mounted file system.

   sudo sh -c ''echo user_allow_other >> /etc/fuse.conf''

4. Optional. By default, the maximum number of file systems that you can mount using FUSE is 1000. If you are running a large number of PDBs and need to configure a separate file system for each PDB, then run the following command to increase the number of file systems that can be mounted using FUSE. The following command increases the number of file systems that can be mounted using FUSE to 4000.

   sudo sh -c ''echo mount_max=4000 >> /etc/fuse.conf''

5. Allow all users to read the fuse.conf file, so that the Oracle process can read this file at run time.

   sudo chmod a+r /etc/fuse.conf

To access files from an OFS mounted on any Cloud environment, you must perform additional steps to configure the environment.

1. Create a directory object using the OFS mount path.

   The following sample code displays how you can create a directory object called pdb1_ofsdir when /u03/dbfs/<pdbid>/data is the OFS mount directory on the db node.

   CREATE DIRECTORY pdb1_ofsdir AS '/u03/dbfs/<pdbid>/data/';

2. Grant access to the user to access the directory object.

   For more information on creating a directory object and setting access permissions on it, see CREATE DIRECTORY in PL/SQL Packages and Types Reference.

You can export an OFS mount to a specified list of nodes and NFS mount it on them. This allows users to access the contents of an OFS mount point from a node where the database is not running. The NFS exports may not work in cloud environments due to security reasons, but you can use it in on-premise environments.

NFS v3 is a stateless protocol because of which it encapsulates each readdir request between opendir and releasedir calls. This may lead to poor performance when you want to list directories that have a large number of files. Therefore, OFS maintains a directory cache which persists across the opendir and releasedir calls. Do not use the no_rbt_cache mount option to avoid inconsistent directory cache listing and to utilize the benefits of directory cache.

Learn about the prerequisites to access storage through NFS server.

Following are the prerequisites:

• DBFS file system must be created before using OFS.

• You should be able to mount the file systems exported by the database.

• NFS server must be configured with KERNEL module.

  Note:

  The KERNEL module is supported through FUSE driver for Linux.

OFS uses the OS authentication model to authorize NFS client users. If the user accesses a local node (where the Oracle instance is running), the access to each file in the file system is controlled through Unix Access Control List set for each object. For NFS clients, you can configure Kerberos to control access.

On Linux, OFS uses FUSE to receive file system requests from the OS kernel or NFS client. This requires user_allow_other parameter to be set in /etc/fuse.conf configuration file if an OS user other than the root user and oracle user need to access the file system.

If the network is not secure, the customer is advised to setup Kerberos to authenticate the user using OS NFS.

• About Kerberos
  Kerberos uses encryption technology, Key Distribution Center (KDC), and an arbitrator to perform secure authentication on open networks.
• Configuring Kerberos Server
  To configure a Kerberos Server in a Linux system: