Oracle Database File System (DBFS) creates a standard file system interface on top of files and directories that are stored in database tables. Oracle DBFS is similar to the Network File System (NFS) protocol in that it provides a shared network file system that looks like a local file system.
Similar to NFS, there is a server component and a client component. The server is Oracle Database and files are stored as SecureFile LOBs in a database table. Because the files are stored in the database you inherit the high availability and disaster-recovery protection Oracle Database offers, providing a full stack disaster-recovery solution. The implementation of the file system in the database is called the DBFS Content Store and allows each database user to create one or more file systems that can be mounted by clients. Each file system has its own dedicated tables that hold the file system content. A set of PL/SQL procedures implement file system access (such as CREATE, OPEN, READ, WRITE, and LIST DIRECTORY) to the database.
Oracle DBFS provides the following benefits:
- The ability to store both non-structured and structured data in the same database.
This allows you to perform backups and synchronous point-in-time recovery of both types of data.
Oracle DBFS provides the ability to store unstructured content in the database by presenting an NFS-like file system to the client. The file system itself is stored in a tablespace in Oracle Database. The database storage aspect is transparent to the client because it appears as a traditional NFS mounted file system with the same functionality, but DBFS provides the ability to store any type of file directly in the database—such as logs or generated reports—that you would normally store in a file system.
- Clustered file system capability with a lightweight process.
You can mount Oracle DBFS on multiple client machines (database servers, mid-tiers) and therefore the file system can also be available for use as a clustered file system. A lightweight process is started on each client machine to make the file system accessible. This process uses the FUSE (Filesystem in Userspace) API to implement the file system access.
- Fast and transparent client failover of both file system and database operations (full stack disaster recovery).
The process on the client systems is OCI based. Thus, clients can take advantage of FAN and Fast Connection Failover capabilities using the same service-based connection methods.
The Oracle Database has been commonly used to store files closely associated with database applications including CAD, medical images, invoice images, documents, etc. The SQL standard data type, BLOB (and CLOB) is used by applications to store files in the database. The Oracle Database provides much better security, availability, robustness, transactions, and scalability than traditional file systems. When files are stored in the database, they are backed up, synchronized to the disaster recovery site using Data Guard, and recovered along with the relational data in the database. This has made storing files in the database an appealing option for many applications.
In Oracle Database 11g, Oracle introduced Oracle SecureFiles LOBs. SecureFiles LOBs provide high performance storage for files, comparable to the performance of traditional file systems. SecureFiles LOBs support advanced features of compression, deduplication and encryption to files. Because SecureFiles LOBs maintain backward compatibility to BLOB (and CLOB), applications written against BLOBs continue to transparantly work against SecureFiles LOBs, even with the previously mentioned features.
Database File System (DBFS) leverages the features of the database to store files, and the strengths of the database in efficiently managing relational data, to implement a standard file system interface for files stored in the database. With this interface, storing files in the database is no longer limited to programs specifically written to use BLOB and CLOB programmatic interfaces. Files in the database can now be transparently accessed using any operating system (OS) program that acts on files. For example, ETL (Extract, Transform and Load) tools can transparently store staging files in the database.
The Oracle Database File System (DBFS) creates a standard file system interface on top of files and directories that are stored in database tables. DBFS is similar to NFS in that it provides a shared network file system that looks like a local file system. Like NFS, there is a server component and a client component.
In DBFS, the server is the Oracle Database. Files are stored as SecureFiles LOBs in a database table. A set of PL/SQL procedures implement the file system access primitives such as create, open, read, write, and list directory. The implementation of the file system in the database is called the DBFS Content Store. The DBFS Content Store allows each database user to create one or more file systems that can be mounted by clients. Each file system has its own dedicated tables that hold the file system content.
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