Once a ®le or directory is open, subsequent requests to perform operations on a ®le or directory can fail. This is because attributes are checked at the server on each request. When permissions on the object are more restrictive at the server, your operations on an open ®le descriptor will fail when NFS receives updates. When the server unlinks the object or makes it unavailable, then your operations on an open ®le descriptor will fail when NFS receives updates. The local Network File System also affects operations that retrieve ®le or directory attributes. Recent changes at the server may not be available at your client yet, and the server may return old values for your operations.

For more information on the usage notes for integrated ®le system APIs, see

System API Reference, SC41-4801.

open(), create(), and mkdir() APIs

If you try to re-create a ®le or directory that was recently deleted, the request may fail. This is because the local data that NFS stores still has a record of the existence of the ®le or directory. File or directory creation will succeed once you update the local data.

fcntl() API

Reading and writing to a ®le with the Network File System relies on byte-range locking to guarantee data integrity. To prevent data inconsistency, use the fcntl() API to get locks and release locks.

For more information about byte-range locking, see ªLocks and Recoveryº on page 74. For more information on the fcntl() API, see System API Reference, SC41-4801.

Unchanged APIs

These APIs do not take a ®le descriptor, directory pointer, or path name, and are not creation functions. Therefore, NFS does not return the EACCES and ESTALE error numbers for the following APIs. All other APIs may receive the EACCESS and ESTALE error numbers.

vgetegid()

vgeteuid()

vgetgid()

vgetgrgid()

vgetgrnam()

vgetgroups()

vgetpwnam()

vgetpwuid()

vgetuid()

vsysconf()

vumask()

Chapter 8. Integrated File System APIs and the Network File System 79

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IBM AS/400E manual Open, create, and mkdir APIs, Fcntl API, Unchanged APIs
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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.
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