R A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T| U| V| W| X| Y| Z| Numerical Listing| RACF (Resource Access Control Facility) The IBM program product offering back-end security in the System/370 MVS and VM environments. RACF had been difficult to use, but Release 1.7 achieved a level of flexibility and usability close to what is offered by leading-edge, third-party software. Computer Associates Top Secret and Access Control Facility-2 (ACF2) are the leading independent software vendor offerings. RAD (Rapid Application Development) A software development technique for doing rapid requirements gathering. It involves working sessions with IS and users, joint requirements definition and agreement, and prototyping. RAID (Redundant Array of Independent Disks) With the exception of RAID 0, all RAID levels provide automated recovery of data in the event of a disk failure. The RAID levels and their key features are: RAID-0 — provides disk striping without parity information; data is written by segment across multiple disks sequentially until the end of the array is reached, and then writing starts at the beginning again. Provides greater logical disk capacity with faster access time on reads (multiple segments read simultaneously). However, RAID-0 provides no data redundancy — if one drive fails, the entire disk array subsystem is unavailable. RAID-1 — provides fault tolerance by using disk mirroring (also called shadowing). Each byte of data on a disk is duplicated on another physical drive, thus providing 100 percent data redundancy. RAID-1 provides immediate access to data when either the primary or secondary drive fails, but it has the highest cost of all RAID types, since duplicate hardware is required. RAID-2 — eliminates the 100 percent redundancy overhead of RAID-1 by using a powerful error detection and correction code (Hamming), with bits of the data pattern written across multiple disks. RAID-3 — similar to RAID-2, but uses a single check disk per group that contains the bit parity of the data disks; data is interleaved across all disks. Because disk reads are performed across the entire array and all data is transferred to the controller in parallel, RAID-3 is well suited for applications that require high data read/write transfer rates for large sequential files. RAID-4 — instead of interleaving blocks of data across all drives, writes the first block on drive 1, the second block on drive 2, and so on. This technique dramatically improves read time, since many reads are single block (single drive), freeing other drives for additional read requests. RAID-5 — eliminates the dedicated parity drive by writing parity with the data across all drives in the array. Consequently, the single-write restriction and some performance degradation of RAID-1 through RAID-4 are eliminated. If a drive fails, the controller can rebuild the data from the parity and data on the remaining drives. RAID-6 — provides two-disk parity and one spare, so that two simultaneous disk failures per array of disks can be tolerated. With the occurrence of a failure, a spare is brought on-line and transparent reconstruction begins automatically in the background with negligible impact on performance. RAID-10 — a combination of RAID-0 and RAID-1 that provides the benefits of striping and fault tolerance (disk mirroring). TOP OF PAGE RAMP-C An IBM proprietary benchmark constructed to measure performance on on-line transaction processing workloads. IBM has used RAMP-C both to measure the relative performance of its processors and architectures and to compare its processors to the competition. It has not released the code, so independent judgments on the relevance of the benchmark are impossible. RARP (Reverse Address Resolution Protocol) A TCP/IP protocol for translating a Data-Link Control address to an IP (Internet Protocol) address. RARP can be used to obtain a logical IP address. Responding to a RARP broadcast from a workstation, a RARP server can send back the IP address. RAS (Reliability, availability, serviceability) A reference to a product’s quality, availability of optional features and ease of diagnosis and repair. Raster Originally a German word naming the screen used in photoengraving; now, the array of scan lines used to cover a planar area to read or depict image information on that area. The electron beam of a TV picture tube writes a raster on the phosphor screen. RCS (Revision Control System) A Unix utility that provides version control. The majority of Unix developers rely on basic utilities such as RCS for version control. RDA (Remote Data Access) A standard (ISO/JCTI/SC21 WG3) to address the interconnection of applications and databases. The standard originally attempted to cover any kind of data access and concerned itself only with effective dialog management, but inherent complexity has encouraged it to focus more on SQL. Rdb (Relational Database) Digital Equipment Corp.’s strategic database management system. Rdb is integrated with the other VAX Information Architecture products, and is designed to provide true multiplatform, distributed database capabilities. RDBMS (Relational Database Management System) A DBMS that incorporates the relational data model, normally including a Structured Query Language application programming interface. A database management system in which the database is organized and accessed according to the relationships between data items. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. Real-Time The description for an operating system that responds to an external event within a short and predictable time frame. Unlike a batch or time-sharing operating system, a real-time operating system provides services or control to independent ongoing physical processes. It typically has interrupt capabilities (so that a less important task can be put aside in deference to a more pressing job) and a priority-scheduling management scheme. Referential Integrity The underlying rules defining the semantic interdependencies among items in a database. The goal is to have those items defined declaratively (i.e., as business-oriented assertions) rather than through procedural logic. A relational database management system should enforce referential integrity as defined by Addendum 1 (X3.135.1-1989) to the American National Standards Institute Structured Query Language standard. TOP OF PAGE Remote Console Operation A remote operator console facility that enables the remote operator to perform normal operational tasks, including storage backup, on a running system. Remote Data Management A form of cooperative processing in which the database management system or file management system executes on a different node than the rest of the application logic. Remote DB2 Read-Only Access Program-level calls allowing midrange system applications remote but direct access to IBM DB2 databases on a System/370 mainframe. At least read-only access is supported. Remote DB2 Update Access Program-level calls allowing midrange system applications remote but direct access to IBM DB2 databases on a System/370 mainframe. Both read-only and update are supported. Remote Environmental Monitoring Hardware and software facilities to permit monitoring of computer room environmentals from a remote site, and to notify remote operators and sound alarms on conditions outside of selectable parameters. Remote File Access Cross-net file access from a process on the midrange system without special coding in the application. Directories or control statements external to the application would be used by the system to locate the file within the network. Remote IMS Read-Only Access Program-level calls allowing midrange system applications remote but direct access to IBM Information Management System databases on a System/370 mainframe. At least read-only access is supported. TOP OF PAGE Remote IMS Update Access Program-level calls allowing midrange system applications remote but direct access to IBM Information Management System databases on a System/370 mainframe. Both read-only and update are supported. Remote Initial Program Load A remote operator console facility that enables the remote operator to initiate as well as continue systems operation after power-on or abnormal system failure. Remote Job Entry (RJE) — BSC Emulation in the midrange system of IBM bisynchronous 2780 or 3780 protocols allowing terminal operators to exchange job control and job output with the mainframe processing queues. Remote Logon A facility to allow an interactive user on one midrange system to log on to any other midrange system of the same supplier in the network. Remote Peripheral Access The ability to attach peripherals logically on other midrange systems in the network to a user’s local process or program. Remote Power-Off A system command facility that when executed results in a full power-off of the midrange system. The command could be invoked by local or remote terminal access to the system or could be time-released as an unattended processing task. Remote Presentation A form of cooperative processing in which the presentation executes on a different node than the rest of the application logic and data management. TOP OF PAGE Remote Software Maintenance — Applications A form of cooperative processing that allows user support groups to control updates and distribution of application system libraries. A facility for predefining the selection and distribution criteria should be included. Remote Software Maintenance System A facility available to a user support group providing for distribution to selected remote midrange system nodes of both new versions and "fixes" to midrange system software (e.g. operating system, database, communications). Remote SQL Database Calls The availability of Structured Query Language database calls at an MS-DOS PC, which provides cross-net access to a relational database on the midrange system. The calls most likely would be syntactically and semantically equivalent to similar calls available on the midrange system. Remote System Monitoring Software facilities to enable monitoring of systems operation from a remote site, and to notify remote operators on conditions outside of selectable parameters. Remote VSAM Read-Only Access Program-level calls allowing midrange system applications remote but direct access to IBM Virtual Storage Access Method files on a System/370 mainframe. At least read-only access is supported. Remote VSAM Update Access Program-level calls allowing midrange system applications remote but direct access to IBM Virtual Storage Access Method files on a System/370 mainframe. Both read-only and update access are supported. Replicated-Site Applications Identical versions of applications that are distributed to remote sites (e.g., sales offices, bank branches, field service offices, insurance agencies, supermarkets and pharmacies) to perform identical roles. Repository A facility for storing descriptions and behaviors of objects in an enterprise, including requirements, policies, processes, data, software libraries, projects, platforms and personnel, with the potential of supporting both software development and operations management. A single point of definition for all system resources. An IBM initiative consisting of a DB2 application that offers a single point of definition for all enterprise objects. It should stimulate both program and installation management productivity. A product or capability offering a single point of definition for all enterprise objects. A systems repository would include configuration definitions, tuning parameters and performance goals, while an applications repository would include data definitions. Requester/Server A type of relationship between two independent programs in which: • Two programs interoperate to carry out the processing for a single unit of application work. • One invokes and directs the other; i.e., the requester program specifies a function to be performed and the server program fulfills that service. TOP OF PAGE Resource Accounting and Chargeback Mechanisms for recording the utilization of resources such as processor time, physical memory, transactions, logical and/or physical input/output operations, disk storage and licensed software, and then reporting such utilization as charged against users, projects, applications or cost centers. Resource Requirements Planning The process of converting the production plan or the master production schedule into the impact on key resources, e.g., man hours, machine hours, storage, standard cost dollars, shipping dollars, and inventory levels. Response Time The time period between a terminal operator’s completion of an inquiry and the receipt of a response. Response time includes the time taken to transmit the inquiry, process it by the computer, and transmit the response back to the terminal. Response time is frequently used as a measure of the performance of an interactive system. REXX (Restructured Extended Executor) A "command language" (job-control language). A structured, interpretive language used to create operator-level command streams to manage and link applications. Introduced in the Virtual Machine environment. RF (Radio Frequency) RF refers to the electromagnetic frequencies used for radio communications. RFI (Request for Information) Notification of an intended acquisition sent to potential suppliers to determine interest and gather general descriptive product materials, though not prices. TOP OF PAGE RFP (Request for Proposal) An invitation for vendors to bid on supplying goods and services. RFT:DCA (Revisable Form Text:Document Content Architecture) The data stream for passing text documents in revisable form under IBM’s second-generation Document Content Architecture. RHC (Regional Holding Company) An RHC is one of seven companies created from the AT&T divestiture, each of which acts as a holding company within a region of the United States for one or more of the 23 divested Bell operating companies, as well as for their unregulated subsidiaries. The RHCs are: Ameritech, Bell Atlantic, BellSouth, NYNEX, Pacific Telesis Group, Southwestern Bell Corp., and US West. RISC (Reduced Instruction Set Computing) A processor architecture that shifts the analytical process of a computational task from the execution or run time to the preparation or compile time. By using less hardware or logic, the system can operate at higher speeds. RISC cuts down on the number and complexity of instructions, on the theory that each one can be accessed and executed faster, and that less semiconductor real estate is required to process them. The result is that for any given semiconductor technology, a more powerful microprocessor can be produced with RISC than with CISC (complex instruction set computing) architectures. The simplification of computer instruction sets to gain processing efficiencies. That theme works because all computers and programs execute mostly simple instructions. RISC has five design principles: Single-cycle execution — In most traditional central processing unit designs, the peak possible execution rate is one instruction per basic machine cycle, and for a given technology, the cycle time has some fixed lower limit. Even on complex CPUs, most compiler-generated instructions are simple. RISC designs emphasize single-cycle execution, even at the expense of synthesizing multi-instruction sequences for some less-frequent operations. Hard-wired control, little or no microcode — Microcode adds a layer of interpretive overhead, raising the number of cycles per instruction, so even the simplest instructions can require several cycles. Simple instructions, few addressing modes — Complex instructions and addressing modes, which entail microcode or multicycle instructions, are avoided. Load/store, register-register design — Only loads and stores access memory; all others perform register-register operations. This tends to follow from the previous three principles. Efficient, deep pipelining — To make convenient use of hardware parallelism without the complexities of horizontal microcode, fast CPUs use pipelining. An n-stage pipeline keeps up to "n" instructions active at once, ideally finishing one (and starting another) every cycle. The instruction set must be carefully tuned to support pipelining. RJE (Remote Job Entry) Refers to a set of communications protocols for input and output of information to a mainframe in a batch mode (as opposed to interactive). TOP OF PAGE RMON (Remote Monitoring) A network management protocol that remotely manages networks providing multivendor interoperability between monitoring devices and management stations. RMS (Record Management System) The basic data management system under Digital Equipment Corp.’s Virtual Machine Storage. ROE (Return on Equity) A measure of a company’s financial performance (net income divided by the value of the stockholders equity, and expressed in percent). Roll-Back Recovery Before and after images of a transaction are maintained in a log file such that, if the system fails, the unsuccessful updates can be backed out, or rolled back. Router Performs a function similar to a local or remote bridge, but routing occurs at Layer 3 of the Open Systems Interconnection reference model. TOP OF PAGE RPC (Remote Procedure Call) A mechanism that extends the notion of a local (i.e., contained in a single address space) procedure call to a distributed computing environment, enabling an application to be distributed among multiple systems in a way that is highly transparent to the application-level code. Examples of RPCs are Apollo’s Network Computing System, Sun Microsystems Open Network Computing, Sybase’s open client/open server and the Open Software Foundation’s Distributed Computing Environment RPC. RS-232-C A technical specification published by the Electronic Industries Association that establishes mechanical and electrical interface requirements between computers, terminals and communications lines. RS-422 A technical specification published by the Electronic Industries Association that establishes mechanical and electrical interface requirements between digital devices. It is incompatible with and has a higher speed capability than RS-232-C. RS-449 A technical standard published by the Electronic Industries Association that provides more extended mechanical and electrical interface functions than those provided by RS-232-C. TOP OF PAGE RS/6000 (RISC System/6000) IBM’s 32-bit technical workstation introduced in mid-1990. It is based on reduced instruction set computer architecture and runs the Unix-based Advanced Interactive Executive (AIX) operating system. Comments? Questions? Entire contents Copyright © 1997, 1998 by Gartner Group, Inc. All rights reserved. Reproduction of this publication in any form without prior written permission is forbidden. Please read the guidelines for customer use of GartnerGroup intellecual property.