• RAID Array Controllers • Workflow Models • PC LAN and System Management Tools Digital Technical Journal Digital Equipment Corporation Volume 6 Number 4 Fall 1994 Editorial Advisory Board Jane C. Blake, Managing Editor Samuel H. Fuller, Chairman Kathleen M. Stetson, Editor Richard W Beane Helen L. Patterson, Editor Donald Z. Harbert Circulation William R. Hawe Richard]. Hoi I ingsworth Catherine M. Phillips, Administrator Richard Lary Dorothea B. Cassady, Secretary F Alan G. Nemeth Production Jean A. Proulx Terri Autieri, Production Editor Robert M. Supnik Anne S. Katzeff, Typographer Gayn B. Winters Peter R. Woodbury, Illustrator The Digital Technicaljournal is a refereed journal published quarterly by Digital Equipment Corporation, 30 Porter Road '"102/D 10, Littleton, Massachusetts 01460. Subscriptions to the journal are $40.00 (non-U.S. $60) for four issues and $75.00 (non-U.S. $115) for eight issues and must be prepaid in U.S. funds. University and college professors and Ph.D. students in the electrical engineering and computer science fields receive complimentary subscriptions upon request. Orders, inquiries, and address changes should be sent to the Digital Technicatjournal at the published­ by address. Inquiries can also be sent electronjcally to [email protected]. Single copies and back issues are available for $16.00 each by calling DECdirect at 1-800-DIGITAL (1-800-344-4825). Recent back issues of thejou·rnal are also available on the Internet at http://www.digital.com/info/DTJ/home.html. Complete Digital internet listings can be obtained by sending an electronic mail message to [email protected]. Digital employees may order subscriptions through Readers Choice by entering vrx PROFILE at the system prompt. Comments on the content of any paper are welcomed and may be sent to the managing editor at the published-by or network address. Copyright© 1995 Digital Equipment Corporation. Copying without fee is permitted provided that such copies are made for use in educational institutions by faculty mem­ bers and are not distributed for commercial advantage. Abstracting with credit of Digital Equipment Corporation's authorship is permitted. All rights reserved. The information in the journal is subject to change without notice and should not be construed as a commitment by Digital Equipment Corporation or by the companies herein represented. Digital Equipment Corporation assumes no responsibility for any errors that may appear in the journal. ISSN 0898-901X Documentation Number EY-Tll8E-TJ The following are trademarks of Digital Equipment Corporation: AXP, Cl, DEC, DEC OSF/1, DECmcc, DECmodel, DECnet, DECwindows, Digital, the DIGITAL logo, HSC, HSC50, HSC60, HSC70, HSC90, HSJ, HSZ, InfoServer, KDM, ManageWORKS, Object Flow, OpenVMS, PATHWORKS, POLYCENTER, Storage Works, ULTRIX, VAX, VAXcluster, VAXstation, VMS, and VMScluster. Apple and AppleShare are registered trademarks of Apple Computer, Inc. dBase IV is a registered trademark of Borland International, Inc. Hewlett-Packard is a registered trademark of Hewlett-Packard Company. Cover Design Our cover design is inspired by a system man­ i960 is a trademark of Intel Corporation. agement topic in this issue. Manage WORKS IBM and NetView are registered trademarks of International Business Machines Corporation. software is a system and network manage­ Knowledge Craft is a registered trademark of Carnegie Group, Inc. ment tool that presents an object-oriented, Microsoft and Visual C++ are registered trademarks and Windows and Windows NT graphical view of a heterogeneous LAN envi­ are trademarks of Microsoft Corporation. ronment. The multi color circles on the cover NFS is a registered trademark of Sun Microsystems, Inc. represent the diverse objects, or entities, on NetWare and Novell are registered trademarks of Novell, Inc. the networks among which a system adminis­ OSF/ I is a registered trademark of the Open Software Foundation, Inc. trato-r "navigates" using the integrated com­ Sun M icrosystems is a registered trademark of Sun Microsystems, Inc. ponents of the tool. UNIX is a registered trademark in the United States and other countries, licensed The cover was designed by Lucinda O'Neill exclusively byX/Open Company Ltd. andjoe Pozerycki,jr:, of Digital's Design X Window System is a trademark of the Massachusetts Institute ofTechnology. Group. Book production was done by Quantic Communications, lnc. Contents I RAID Array Controllers 5 The Architecture andDesign of HS-series StorageWorks Array Controllers Stephen]. Sicola Wo rkflow Models 26 Policy Resolution in Workflow Management Systems Christoph ]. BuBier 50 TheDesign ofDECmodel for Windows Stewart V Hoover and Gary L. Kratkiewicz PC LAN and System Management Tools 63 TheDesign of ManageWORKS: A User Interface Framework Dennis G. Giokas and John C. Rokicki 75 The Structure of the OpenVMS Management Station James E. Johnson 89 Automatic, Network-directed Operating System Software Upgrades: A Platform-independent Approach John R. Lawson, Jr. Editor's Introduction I explain the reasoning behind the creation of a pre­ sentation layer in DECmoc.lel that provides a graphi­ cal view of the business process while hiding the technical details of the model. The authors also cover implementation details, including the deci­ sions to move from the original !.IS!' environment to a C:++ programming environment and to imple­ ment the knowledge base fo r DECmodel in ROCK, a frame-based .knowledge representation. We then shift the fo cus to ManageWORKS and POLYCENTER tools that have been developed to simplify the increasingly complicated job of system Jane C. Blake Ma naging Editor management. The first of three papers describes the development of the ManageWORKS Workgroup Administrator software. Dennis Giokas ami John Three computing topics are presented in this issue Rokicki discuss the design principles adopted for of the journal: a storage array controller fo r open this product that enables system and network man­ system environments, workflow architectures and agement of heterogeneous L.ANs from a single PC tools, ancl PC andlAN system management products. running Microsoft Windows. Key design elements The opening paper, by Steve Sicola, describes are plug-in, customizable modules fo r system Digital's new HS series of StorageWorks array con­ navigation ancl management, ami the user inter­ trollers. Designed fo r open systems, the control­ fa ce framework, which controls the flow between lers interface to host computers by means of the modules. The authors offer scenarios to illustrate industry-standard SCSI-2 interconnect, as well as interactions between components. Digital's CI and OSSI host interconnects. Equally Managing OpenVMS systems from a PC running important to designers as openness were controller the Microsoft Windows operating system can be availability and perfo rmance. Innovative fe atures accomplished with the OpenVMS Management were introduced, including dual-redundant con­ Station, of which ManageWORKS is a key compo­ trol lers and Parity RAID firmware to ensure high nent. Jim Johnson defines the need fo r this scalable availability, and a write-back cache that significantly and secure client-server tool in OpenVMS envi­ improves performance. The paper concludes with ronments, which can be clustered, distributed, a description of the common controller processing expanded, and networked extensively. After a dis­ core fo r the SCSI, CI, and DSSI controller variants. cussion of design alternatives, Jim describes the Workflow is the subject of two papers with dif­ fu nctions of the Station's client, communication, fe ring perspectives. Christoph BuBier opens his and server components. paper with introductory definitions and impI ica­ The final paper is about an initial system load tions of workflow concepts. He argues that a \ovork­ (ISL) capability fo r automatic, network-directed. flow that uses roles fo r task assignment is limited, operating system software upgrades. John Lawson especially in large. international enterprises. He reviews goals for the POLYCENTER Software Distri­ states that by adding the dimension of organiza­ bution layered product, compares the POLYCENTER tional dependencies fo r task assignment a complex ISL process with the OpenV:VIS ISL process. and workflow is more precisely expressed. Using the steps through the requirements for expanding the example of a travel expense reimbursement work­ l'OLYCENTER Sofnvare Distribution capability to flow, Christoph shows how the Policy Resolution other platforms and operating systems. Architecture design principles support enterprise­ Our next issue will celebrate the Journal's tenth level workflow deployment-reusability, security, anniversary of publishing the technical achieve­ generality, dynamics, and distribution. He also dis­ ments of Digital's engineers and partners. The issue cusses the Policy Definition Language that formally will feature database technologies and new Alpha describes workJlow elements. workstations ancl high-end server systems. A second paper about workflow presents a tool, called DECmodel fo r Windows, fo r the development of business process models and their graphical presentation. Stew Hoover and Gary Kratkiewicz 2 Biographies I Christoph J. BuBier Christoph BuGler is a faculty member at the Technical University of Darmstadt, Germany, where he is pursuing a Ph.D. degree. His research is in workflow and organization modeling, with a fo cus on organizational embec.lcling of workflow management, ancJ in architectures fo