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[vj.jain]

Oracle 11g has introduced a new method for accessing NFS V3 servers directly using an internal “Direct NFS Client” as part of the Oracle Database kernel. This improves performance and manageability by allowing Oracle-specific optimizations to be utilized. Additionally, it removes the need to manually configure and tune most of the NFS client parameters.

Files used by the database can be stored on the NFS drive including data files. However, due to the performance limitations of NFS storage prior to Oracle 11g, many production databases opted to use network storage for less critical files and processes. Using NFS drives allows for scalability of disk space without requiring an upgrade of the existing architecture. Instead, the system administrator can attach a network drive and access the drive as if it was attached locally. Once the network drive is available, data files can be moved or created in the newly available drives.

The direct NFS client has two fundamental optimizations that increase performance. First, the direct NFS client is capable of performing concurrent direct I/O, removing the need to utilize the operating system’s cache and bypassing limitations imposed by the operating system configuration. When using the operating system to configure the NFS client, when data is written from the database to the NFS, it requires that the data be read from Oracle’s memory to the operating system cache before it is copied from the system cache to the NFS. By using the direct NFS client, the Oracle data no longer needs to be cached in the operating system, reducing the overall memory consumption and kernel CPU when writing to the network drive.


For more information about the Direct NFS Client, make sure you get a copy of Oracle 11g New Features Guide by John Garmany, Steve Karam, Lutz Hartmann, V. J. Jain, and Brian Carr http://www.oracle-developer.com/oracle_11g_new_features.html