DCE Enhanced Distributed
File System for AIX

POWER access to data


Physical view of sample EDFS cell


Why DCE?

Many corporations are faced with collections of computing today that do not match their business goals. They need a comprehensive and open infrastructure upon which to re-engineer business applications.

In response to this demand, IBM is investing in DCE technologies across all of its platforms. Starting with code licensed from the Open Software Foundation®, IBM has developed DCE offerings allowing customers maximum flexibility in distributed application design. EDFS is based on DCE Version 1.1 technology from the Open Software Foundation with IBM enhancements.

The goal is to extend the power and availability of traditional IBM mainframe environments throughout the enterprise. IBM is committed to a continued roll-out of DCE-based solutions and services to meet the large scale client/server requirements of today's businesses.

Logical view of sample DFS global namespace

Business problem: access to data

Businesses have a need to share all kinds of data, including bulletin board notices, operations manuals, and even computer programs. Their goal is to store and manage the data centrally while making it easily and reliably available to users on the network.

The AIX EDFS allows data sharing with the reliability and manageability characteristics required by most corporations today. Because DFS is an application built on top of the DCE technology infrastructure, it inherits all of the underlying benefits - security, scalability, availability, interoperability and the ability to operate over wide-area networks (WANs).

As corporations begin to "up-size" from today's departmental local area networks (LANs), they are looking for centralized administration and enterprise directory services. EDFS is designed to meet these needs.

A global view architected for performance

Users access and interact with DFS files in the same way they would their local files. (POSIX(tm) single-site file semantics, including byte-range locking, are preserved across the network.) All DFS files are part of a single global namespace. Users can access data anywhere in the network without knowing its physical location; they only have to know its name!

The data can actually reside in the DFS physical file system, LFS, or in a native file system, such as the AIX Journalled File System (JFS), or AIX CD-ROM file system. The DFS server takes data stored by the physical file system and makes it available to clients through its file exporter. For example, Ms. Jones has a document in a file called /.../ibm/usr/jones/note and Mr. Brown, in a remote city, can access it using the same name. NFS clients can access unprotected DFS data or secured DFS data if they use the AIX NFS/DFS Authenticating Gateway. AFS clients can access DFS data through a vendor gateway.

Each DFS client in the network accesses files through its cache manager. For example, when you first open a spreadsheet, it is cached into local memory or disk where it is available for subsequent use. What are the benefits?

DFS maintains cache coherency among clients, ensuring data integrity. All of this is part of the basic DFS services in the AIX DCE Base Services product.


Higher levels of availability and performance
The enhanced features of EDFS add additional levels of scalability and manageability to base DFS. EDFS also ensures higher availability through features such as the LFS, which is a robust, log-based physical file system, and data replication across EDFS servers, which distributes server loads.

Smart data organization and tools
Administrative tasks are greatly simplified through the EDFS data organization and tools. The concept of data being contained in "filesets" provides a convenient way to group administrative tasks, such as data backup, relocation and replication. The EDFS filesets are location-independent, so they can be transparently replicated or moved to another aggregate for load balancing.

Centralized security control

DFS uses DCE's Kerberos(tm) style of security to ensure that users are who they say they are. EDFS access control lists allow or deny users access to data and programs with a high degree of granularity. This is important for intercompany as well as intracompany collaboration and sharing of information.

AIX EDFS Data Organization

NFS to DFS Authenticating Gateway

For those environments using NFS today, IBM provides a secure gateway product for any NFS client to access data stored in the AIX DFS filesystem. AIX PC-NFS authentication service is integrated with this gateway to DFS.

AIX DCE EDFS at work

EDFS is very effective in making large amounts of data available to many users in an enterprise environment.

Here are some examples where you can effectively put the advanced features of EDFS to work for you as a repository for:

Features and Benefits

Heterogeneous transparent file sharing

Uniform global namespace



Data consistency

Centralized administration

Data replication

Enhanced Distributed File System

NFS/DFS Authenticating Gateway

AIX DFS at a glance

Hardware requirements

Memory requirements*

Fixed-disk requirements** (approximate)

Operating system

Packaging and installation

*These requirements do not take other application demands into consideration.
**Consult your IBM marketing representative for more current information, including paging space requirements.
***AIX DCE Base Services must also be installed.

For more information on the RISC System/6000 products, call your IBM marketing representative or IBM Business Partner; or
Access http://www.austin.ibm.com on the Internet to get to the RS/6000 Products and Services page on IBM's World Wide Web server, and then select the Software option.
Call 1 800 IBM-CALL (1 800 426-2255) to reach IBM DIRECT. In Canada, call 1 800 363-RISC (1 800 363-7472).
Call 1 800 IBM-4FAX (1 800 426-4329) to have information faxed to your location.

International Business Machines Corporation 1995

IBM Corporation
Department 69B
RISC System/6000 Division
Route 100
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Produced in the United States of America
All Rights Reserved

References in this publication to IBM products or services do not imply that IBM intends to make them available in all countries in which IBM operates.

Photographs show engineering and design models. Changes may be incorporated in production models.

This equipment is subject to FCC rules. It will comply with the appropriate FCC rules before final delivery to the buyer.

The RISC System/6000® and AIX family of products are developed and manufactured under ISO 9000 registered quality systems.

AIX, IBM, RISC System/6000 are registered trademarks of International Business Machines Corporation.
CICS and RS/6000 are trademarks of International Business Machines Corporation.
Open Software Foundation is a registered trademark of Open Software Foundation, Inc.
POSIX is a trademark of the Institute of Electrical and Electronic Engineers (IEEE).

All other products are trademarks or registered trademarks of their respective companies

G221-4308-01 / G2214308

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