For example, the ®le system/home/sweet/home has been exported, and /home/sweet is a parent directory of /home/sweet/home. You cannot now export /home/sweet unless it exists on a different local ®le system.

4.You can only export local ®le systems. Any ®le systems or proper subsets of ®le systems that exist on remote systems cannot be exported except by those remote systems.

For example, /help exists on a different server than the one you are currently

accessing. You must be able to access that remote server in order to export

/help.

A more complicated example involves trying to export a ®le system which a

local client mounts from a remote server. For example, the ®le system /home/troupe resides on a local client, and the ®le system/remote1 exists on a remote server. If the client mounts /remote1 over /home/troupe, then the client cannot export /home/troupe. This is because it actually exists on a remote server and not the local client.

The ®rst rule allows you to export only selected portions of a large ®le system. You can export and mount a single ®le, a feature which is used extensively by clients without local disks. The second and third rules say that you can export a local ®le system in one way, and one way only. Once you export a sub-directory of a ®le system, you cannot go upstream and export the whole ®le system. Also, once you have made the entire ®le system public, you cannot restrict thedownstream ¯ow of the export to include only a few ®les.

Exporting sub-directories is similar to creating views on a relational database. You choose the portions of the database that a user needs to see, hiding information that is either extraneous or con®dential. In this way, system administrators can limit access to sensitive material.

CHGNFSEXP (Change Network File System Export) Command

Purpose

The Change Network File System Export (CHGNFSEXP) command adds directory names to (exports) the list of directory trees that are currently exported to NFS clients (the export table). This command also removes (unexports) the list of directory trees that are currently exported to NFS clients. The ¯ags in the OPTIONS list indicate what actions you want the CHGNFSEXP command to perform. For a complete description of CHGNFSEXP options, see CL Reference, SC41-4722.

A list of directories and options for exporting a ®le system and its contents is stored in the /etc/exports ®le. The CHGNFSEXP command allows you to export all of the

directory trees speci®ed in the ®le using the '-A' ¯ag. CHGNFSEXP also allows you

to export a single directory tree by specifying the directory name. When the directory tree being exported exists in the /etc/exports ®le, you can export it with

the options speci®ed there, or you can use the '-I' ¯ag to override the options, specifying the new options on the CHGNFSEXP command.

You can also export a directory tree not previously de®ned in the/etc/exports ®le by providing the '-I' and the options for it on the CHGNFSEXP command. You can unexport directory trees by using the '-U' ¯ag on the CHGNFSEXP command. You can unexport any ®le systems that you have previously exported, even if remote clients have mounted them. The result is that the NFS server will send the remote clients the ESTALE error number on their next attempt to operate on an object in that ®le system.

30OS/400 Network File System Support V4R4

Page 47 Page 49
Page 48
Image 48
IBM AS/400E manual Chgnfsexp Change Network File System Export Command, Purpose
Page 47 Page 49

AS/400E specifications

The IBM AS/400E, now more commonly known as IBM i, is a robust and versatile midrange server that has been designed to provide a comprehensive computing solution for businesses of all sizes. First introduced in the late 1980s, the AS/400 series has undergone multiple enhancements and rebranding, with the AS/400E being one of the notable iterations. This powerful platform is closely associated with IBM's commitment to reliability, scalability, and integrated business solutions.

One of the main features of the AS/400E is its highly integrated architecture that combines hardware and software into a cohesive system. This integration allows for seamless operations, reducing the complexity typically associated with managing disparate systems. The system is powered by IBM's proprietary OS/400 operating system, which has evolved into IBM i, featuring advanced capabilities like object-oriented programming, integrated database management, and security features that are essential for enterprise environments.

A key characteristic of the AS/400E is its robust database support, primarily through the use of DB2 for i. This integrated database management system enables efficient data handling and retrieval, facilitating real-time business analytics and reporting. Furthermore, the platform supports a variety of programming languages, including RPG, COBOL, and Java, making it flexible for developers who require diverse tools for application development.

The AS/400E is also known for its exceptional reliability and uptime, making it a preferred choice for critical business applications in industries such as finance, healthcare, and manufacturing. This reliability is backed by advanced error detection and correction mechanisms, as well as redundancy features that help prevent data loss and minimize downtime.

In terms of scalability, the AS/400E can effortlessly expand to accommodate growing business demands. Organizations can increase processing power by adding more resources without significant disruption. This scalability, combined with the system’s built-in virtualization capabilities, allows businesses to optimize resource usage and streamline operations.

Security is another defining feature of the AS/400E. The platform incorporates various layers of security measures, including user authentication, encryption, and comprehensive auditing capabilities, ensuring that sensitive business data is protected against unauthorized access.

Overall, the IBM AS/400E remains a powerful tool in the enterprise computing landscape, providing businesses with an integrated, reliable, and secure solution for their technological needs. Its enduring popularity is a testament to its capability to evolve with changing business requirements while maintaining its core attributes of high performance and stability.
Top Page Image Contents