Data Cache

 

The data cache is very similar to the directory and ®le attribute cache in that it

 

stores frequently used information locally on the client. The data cache, however,

 

stores data that is frequently or likely to be used instead of ®le or directory

 

attributes. The data cache provides data in cases where the client would have to

 

access the server to retrieve information that has already been read. This operation

 

improves the performance of NFS.

 

Whenever a user makes a request on a remote object, a request is sent to the

 

server. If the request is to read a small amount of data, for example, 1 byte (B),

 

then the server returns 4 kilobytes (KB) of data. This ªextraº data is stored in the

 

client caches because, presumably, it will soon be read by the client.

 

When users access the same data frequently over a given period of time, the client

 

can cache this information to prevent a client/server interaction. This caching also

 

applies to users who use data in one ªareaº of a ®le frequently. This is calledlocality

 

and involves not only the primary data that is retrieved from the server, but also a

 

larger block of data around it. When a user requests data frequently from one area,

 

the entire block of data is retrieved and then cached. There is a high probability that

 

the user will soon want to access this surrounding data. Because this information is

 

already cached locally on the client, the performance of NFS is improved.

 

Client Timeout

 

If the client does not have a cache loaded, then all requests will go to the server.

 

This takes extra time to process each client operation. With the mount command,

 

users can specify a timeout value for re-sending the command. The mount

 

command can not distinguish between a slow server and a server that does not

 

exist, so it will retry the command.

The default retry value is 2 seconds. If the server does not respond in this time,

then the client will continue to retry the command. In a network environment, this

can overload the server with duplicate AS/400 client requests. The solution to this

difficulty is to increase the timeout value on the mount command to 5-10 seconds.

14OS/400 Network File System Support V4R4

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IBM AS/400E manual Data Cache, Client Timeout
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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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