Oracle DBA

Direct NFS (Direct Network File System) is a feature integrated into Oracle Database software designed to optimize the interaction between Oracle Database and NFS (Network File System) storage devices. It offers several benefits, including improved performance, scalability, and simplified configuration for Oracle Database deployments that use NFS storage for various database-related files.

Direct NFS Client, a component of Direct NFS, is responsible for integrating the NFS client functionality directly into Oracle Database. This integration streamlines the I/O (Input/Output) path between the database and NFS server, resulting in significant performance improvements. Direct NFS Client is highly optimized for Oracle Database workloads, making it more efficient than traditional operating system NFS clients.

Key aspects of Direct NFS include:

1. NFS Protocol Support: Direct NFS Client supports multiple NFS protocol versions, including NFSv3, NFSv4, NFSv4.1, and pNFS. This flexibility ensures compatibility with various NFS server configurations.
2. Direct NFS Dispatcher: Starting with Oracle Database 12c Release 2, Direct NFS introduces the Direct NFS dispatcher, which consolidates the number of TCP connections created between a database instance and the NFS server. This feature is particularly valuable in large database deployments and parallel NFS setups, improving scalability and network performance.
3. Mount Point Management: Direct NFS Client can obtain NFS mount points from either the operating system’s mount entries or the oranfstab file. This flexibility simplifies the management of NFS mount points.
4. Requirements: To work effectively with Direct NFS Client, NFS servers must meet specific requirements, such as having write size values (wtmax) of 32768 or greater. Additionally, NFS mount points should be mounted by both the operating system kernel NFS client and Direct NFS Client, even when Direct NFS Client is configured to provide file service.
5. Error Handling: If Oracle Database encounters issues connecting to an NFS server using Direct NFS Client, it can revert to using the operating system kernel NFS client, and it logs informational messages to indicate the fallback.
6. Mount Point Search Order: Direct NFS Client searches for NFS mount entries in a specific order, with the first matching entry used as the mount point.
7. Single Active NFS Client Implementation: Each Oracle Database instance can have only one active NFS Client implementation. Enabling Direct NFS Client on an instance prevents the use of other NFS Client implementations, such as the kernel NFS Client.

The below information explains how to create an oranfstab file for Oracle Direct NFS Client configuration. This file is used to define the attributes of NFS servers that you want to access using Direct NFS Client. Each NFS server entry in the oranfstab file should have the following attributes:

1. server: The name of the NFS server.
2. local: Up to four paths on the database host, specified by IP address or name.
3. path: Up to four network paths to the NFS server, specified by IP address or name.
4. export: The exported path from the NFS server.
5. mount: The corresponding local mount point for the exported volume.
6. mnt_timeout: Specifies the time (in seconds) that Direct NFS Client should wait for a successful mount before timing out. This parameter is optional, with a default timeout of 10 minutes (600 seconds).
7. nfs_version: Specifies the NFS protocol version used by Direct NFS Client, such as NFSv3, NFSv4, NFSv4.1, or pNFS. The default version is NFSv3.
8. security_default: Specifies the default security mode applicable for all the exported NFS server paths for a server entry. The default value is “sys” (UNIX-level security).
9. security: Specifies the security level for enabling security using Kerberos authentication with Direct NFS Client. Supported security levels include “sys” (default), “krb5,” “krb5i,” and “krb5p.”
10. dontroute: An optional parameter that specifies that outgoing messages should not be routed by the operating system but instead sent using the bound IP address.
11. management: Enables Direct NFS Client to use the management interface for SNMP queries, with the default value being the server parameter value.
12. community: Specifies the community string for use in SNMP queries, with the default value being “public.”

Direct NFS (Direct Network File System) is a feature integrated into Oracle Database that optimizes the interaction between Oracle Database and Network File System (NFS) storage devices. It enhances performance and scalability while simplifying configuration. Direct NFS supports various NFS protocol versions, ensuring compatibility with different NFS server setups.

Introduced in Oracle Database 12c Release 2 and later, the Direct NFS dispatcher consolidates TCP connections, especially valuable in large or parallel NFS deployments, improving scalability and network performance. Configuration involves creating an oranfstab file that defines NFS server attributes and mount points. In case of connection issues, Oracle Database seamlessly switches to the kernel NFS client. Overall, Direct NFS streamlines NFS storage utilization, enhancing database efficiency and performance.