To our knowledge, no previous study has examined the system-level effects of soft errors on the availability and reliability of data storage systems. In this paper, we first analyze the effects of soft errors occurring in the server processors of storage controllers on the entire storage system dependability. We then propose a new metric, Storage System Vulnerability Factor , to accurately capture the impact of soft errors in storage systems.
However, soft errors in the rest of cache memory filled by Operating System and storage applications will result in Data Unavailability at the storage system level. Let us first examine system complexity based on cardinality, or size.
The original computer hardware metric is transistor count on an integrated circuit. There are many problems that can result from faulty assumption made by the development team. An example of this factor causing major problems can be windows 0xF found in the experience of Nuclear Regulatory Commission. A dialog box, or pop-up message, appears in a window on the screen, blocking further interaction with the computer until it is acknowledged.
It accepts requests from the device drivers in the operating system as well from application programs. It also contains autostart functions that test the system on startup and prepare the computer for operation. It loads the operating system and passes control to it. IEEE Pertaining to a system or mode of operation in which inputs are collected and processed all at one time, rather than being processed as they arrive, and a job, once started, proceeds to completion without additional input or user interaction.
Contrast with conversational, interactive, on-line, real time. Execution of programs serially with no interactive processing. Contrast with real time processing. The signalling rate of a line. It's the switching speed, or number of transitions [voltage or frequency change] made per second. At low speeds bauds are equal to bits per seconds; e. However, one baud can be made to represent more than one bit per second. A measure of how closely the mean value in a series of replicate measurements approaches the true value.
See: accuracy, precision, calibration. A contraction of the term binary digit. The bit is the basic unit of digital data. It may be in one of two states, logic 1 or logic 0. It may be thought of as a switch which is either on or off. Bits are usually combined into computer words of various sizes, such as the byte. A measure of the speed of data transfer in a communications system. ISO 1 A string of records, words, or characters that for technical or logical purposes are treated as a unity.
ISO The part of the error control procedure that is used for determining that a block of data is structured according to given rules. NIST A diagram of a system, instrument or computer, in which the principal parts are represented by suitably annotated geometrical figures to show both the basic functions of the parts and the functional relationships between them.
ISO The process, initiated by a single action, of transferring one or more blocks of data. ISO The number of records in a block. The number is computed by dividing the size of the block by the size of each record contained therein.
Syn: grouping factor. A trojan horse which attacks a computer system upon the occurrence of a specific logical event [logic bomb], the occurrence of a specific time-related logical event [time bomb], or is hidden in electronic mail or data and is triggered when read in a certain way [letter bomb].
See: trojan horse, virus, worm. Pertaining to the principles of mathematical logic developed by George Boole, a nineteenth century mathematician. Boolean algebra is the study of operations carried out on variables that can have only one of two possible values; i. In Pascal a boolean variable is a variable that can have one of two possible values, true or false. A boot program, in firmware, typically performs this function which includes loading basic instructions which tell the computer how to load programs into memory and how to begin executing those programs.
A distinction can be made between a warm boot and a cold boot. A cold boot means starting the system from a powered-down state. A warm boot means restarting the computer while it is powered-up. Important differences between the two procedures are; 1 a power-up self-test, in which various portions of the hardware [such as memory] are tested for proper operation, is performed during a cold boot while a warm boot does not normally perform such self-tests, and 2 a warm boot does not clear all memory.
IEEE A short computer program that is permanently resident or easily loaded into a computer and whose execution brings a larger program, such an operating system or its loader, into memory. NBS A selection technique in which test data are chosen to lie along "boundaries" of the input domain [or output range] classes, data structures, procedure parameters, etc. Choices often include maximum, minimum, and trivial values or parameters.
This technique is often called stress testing. See: testing, boundary value. IEEE A control flow diagram consisting of a rectangle that is subdivided to show sequential steps, if-then-else conditions, repetition, and case conditions.
Syn: Chapin chart, Nassi-Shneiderman chart, program structure diagram. See: block diagram, bubble chart, flowchart, graph, input-process-output chart, structure chart. An instruction which causes program execution to jump to a new point in the program sequence, rather than execute the next instruction. Syn: jump. Myers A test case identification technique which produces enough test cases such that each decision has a true and a false outcome at least once.
Contrast with path analysis. NBS A test coverage criteria which requires that for each decision point each possible branch be executed at least once.
Syn: decision coverage. Contrast with condition coverage, multiple condition coverage, path coverage, statement coverage. See: testing, branch. IEEE A data flow, data structure, or other diagram in which entities are depicted with circles [bubbles] and relationships are represented by links drawn between the circles. See: block diagram, box diagram, flowchart, graph, input-process-output chart, structure chart. A device or storage area [memory] used to store data temporarily to compensate for differences in rates of data flow, time of occurrence of events, or amounts of data that can be handled by the devices or processes involved in the transfer or use of the data.
A fault in a program which causes the program to perform in an unintended or unanticipated manner. See: anomaly, defect, error, exception, fault. A common pathway along which data and control signals travel between different hardware devices within a computer system. A When bus architecture is used in a computer, the CPU, memory and peripheral equipment are interconnected through the bus. B When bus architecture is used in a network, all terminals and computers are connected to a common channel that is made of twisted wire pairs, coaxial cable, or optical fibers.
Ethernet is a common LAN architecture using a bus topology. A general purpose high-level programming language. Created for use in the development of computer operating systems software. It strives to combine the power of assembly language with the ease of a high-level language.
Ensuring continuous adequate performance of sensing, measurement, and actuating equipment with regard to specified accuracy and precision requirements. See: accuracy, bias, precision. IEEE A diagram that identifies the modules in a system or computer program and shows which modules call one another. Note: The result is not necessarily the same as that shown in a structure chart.
Syn: call tree, tier chart. Contrast with structure chart. See: control flow diagram, data flow diagram, data structure diagram, state diagram. Myers A Boolean graph linking causes and effects.
The graph is actually a digital-logic circuit a combinatorial logic network using a simpler notation than standard electronics notation. The input and output domains are partitioned into classes and analysis is performed to determine which input classes cause which effect.
A minimal set of inputs is chosen which will cover the entire effect set. See: testing, functional. The unit of a computer that includes the circuits controlling the interpretation of program instructions and their execution.
The CPU controls the entire computer. It receives and sends data through input-output channels, retrieves data and programs from memory, and conducts mathematical and logical functions of a program. ANSI In computer systems, a technical evaluation, made as part of and in support of the accreditation process, that establishes the extent to which a particular computer system or network design and implementation meet a prespecified set of requirements.
Change control is a vital subset of the Quality Assurance [QA] program within an establishment and should be clearly described in the establishment's SOPs. See: configuration control. A technique for error detection to ensure that data or program files have been accurately copied or transferred. Basically, a redundant check in which groups of digits; e. Contrast with cyclic redundancy check [CRC], parity check. See: checksum. IEEE A sum obtained by adding the digits in a numeral, or group of numerals [a file], usually without regard to meaning, position, or significance.
See: check summation. A term used in a broad sense to describe the relationship between the receiver and the provider of a service. In the world of microcomputers, the term client-server describes a networked system where front-end applications, as the client, make service requests upon another networked system.
Client-server relationships are defined primarily by software. In a local area network [LAN], the workstation is the client and the file server is the server. However, client-server systems are inherently more complex than file server systems. Two disparate programs must work in tandem, and there are many more decisions to make about separating data and processing between the client workstations and the database server.
The database server encapsulates database files and indexes, restricts access, enforces security, and provides applications with a consistent interface to data via a data dictionary. ISO A device that generates periodic, accurately spaced signals used for such purposes as timing, regulation of the operations of a processor, or generation of interrupts. High-capacity cable used in communications and video transmissions.
Provides a much higher bandwidth than twisted wire pair. A high-level programming language intended for use in the solution of problems in business data processing.
IEEE An independent review of source code by a person, team, or tool to verify compliance with software design documentation and programming standards. Correctness and efficiency may also be evaluated. Contrast with code inspection, code review, code walkthrough.
See: static analysis. A software tool which examines source code for adherence to coding and documentation conventions. Contrast with code audit, code review, code walkthrough. This technique can also be applied to other software and configuration items. Syn: Fagan Inspection. IEEE A meeting at which software code is presented to project personnel, managers, users, customers, or other interested parties for comment or approval.
Contrast with code audit, code inspection, code walkthrough. Contrast with code audit, code inspection, code review. IEEE 1 In software engineering, the process of expressing a computer program in a programming language. See: implementation. Written procedures describing coding [programming] style conventions specifying rules governing the use of individual constructs provided by the programming language, and naming, formatting, and documentation requirements which prevent programming errors, control complexity and promote understandability of the source code.
Syn: development standards, programming standards. A compact disk used for the permanent storage of text, graphic or sound information. Digital data is represented very compactly by tiny holes that can be read by lasers attached to high resolution sensors.
Capable of storing up to MB of data, equivalent to , pages of text, or 20, medium resolution images. This storage media is often used for archival purposes. Syn: optical disk, write-once read-many times disk.
IEEE A software tool that compares two computer programs, files, or sets of data to identify commonalities or differences. Typical objects of comparison are similar versions of source code, object code, data base files, or test results. ANSI The capability of a functional unit to meet the requirements of a specified interface.
NIST Translating a program expressed in a problem-oriented language or a procedure oriented language into object code. Contrast with assembling, interpret. See: compiler. See: assembler, interpreter, cross-assembler, cross-compiler. A type of integrated circuit widely used for processors and memories. It is a combination of transistors on a single chip connected to complementary digital circuits.
NIST The property that all necessary parts of the entity are included. Completeness of a product is often used to express the fact that all requirements have been met by the product. See: traceability analysis. Traditional computer architecture that operates with large sets of possible instructions. Most computers are in this category, including the IBM compatible microcomputers. As computing technology evolved, instruction sets expanded to include newer instructions which are complex in nature and require several to many execution cycles and, therefore, more time to complete.
Computers which operate with system software based on these instruction sets have been referred to as complex instruction set computers. Contrast with reduced instruction set computer [RISC]. IEEE 1 The degree to which a system or component has a design or implementation that is difficult to understand and verify.
IEEE 1 A functional unit that can perform substantial computations, including numerous arithmetic operations, or logic operations, without human intervention during a run. The use of computers to design products. CAD systems are high speed workstations or personal computers using CAD software and input devices such as graphic tablets and scanners to model and simulate the use of proposed products.
CAD software is available for generic design or specialized uses such as architectural, electrical, and mechanical design. CAD software may also be highly specialized for creating products such as printed circuits and integrated circuits. The automation of manufacturing systems and techniques, including the use of computers to communicate work instructions to automate machinery for the handling of the processing [numerical control, process control, robotics, material requirements planning] needed to produce a workpiece.
An automated system for the support of software development including an integrated tool set, i. ANSI A complete set of the operators of the instructions of a computer together with a description of the types of meanings that can be attributed to their operands.
Syn: machine instruction set. IEEE A language designed to enable humans to communicate with computers. See: programming language. ISO The branch of science and technology that is concerned with methods and techniques relating to data processing performed by automatic means.
ANSI a functional unit, consisting of one or more computers and associated peripheral input and output devices, and associated software, that uses common storage for all or part of a program and also for all or part of the data necessary for the execution of the program; executes user-written or user-designated programs; performs user-designated data manipulation, including arithmetic operations and logic operations; and that can execute programs that modify themselves during their execution.
A computer system may be a stand-alone unit or may consist of several interconnected units. See: computer, computerized system. ISO An examination of the procedures used in a computer system to evaluate their effectiveness and correctness and to recommend improvements. See: software audit. IEEE The protection of computer hardware and software from accidental or malicious access, use, modification, destruction, or disclosure.
Security also pertains to personnel, data, communications, and the physical protection of computer installations. See: bomb, trojan horse, virus, worm. A sequence of bits or characters that is stored, addressed, transmitted, and operated on as a unit within a given computer. Typically one to four bytes long, depending on the make of computer. Includes hardware, software, peripheral devices, personnel, and documentation; e.
See: computer, computer system. IEEE The initial phase of a software development project, in which user needs are described and evaluated through documentation; e. Myers A test coverage criteria requiring enough test cases such that each condition in a decision takes on all possible outcomes at least once, and each point of entry to a program or subroutine is invoked at least once.
Contrast with branch coverage, decision coverage, multiple condition coverage, path coverage, statement coverage. Application software, sometimes general purpose, written for a variety of industries or users in a manner that permits users to modify the program to meet their individual needs.
IEEE 1 The arrangement of a computer system or component as defined by the number, nature, and interconnections of its constituent parts. IEEE An element of configuration management, consisting of the evaluation, coordination, approval or disapproval, and implementation of changes to configuration items after formal establishment of their configuration identification.
See: change control. IEEE An element of configuration management, consisting of selecting the configuration items for a system and recording their functional and physical characteristics in technical documentation. IEEE An aggregation of hardware, software, or both that is designated for configuration management and treated as a single entity in the configuration management process.
See: software element. IEEE A discipline applying technical and administrative direction and surveillance to identify and document the functional and physical characteristics of a configuration item, control changes to those characteristics, record and report change processing and implementation status, and verifying compliance with specified requirements.
See: configuration control, change control, software engineering. IEEE The degree of uniformity, standardization, and freedom from contradiction among the documents or parts of a system or component.
See: traceability. A software tool used to test requirements in design specifications for both consistency and completeness. A value that does not change during processing. Contrast with variable. IEEE 1 Evaluation of the safety of restrictions imposed on the selected design by the requirements and by real world restrictions.
The impacts of the environment on this analysis can include such items as the location and relation of clocks to circuit cards, the timing of a bus latch when using the longest safety-related timing to fetch data from the most remote circuit card, interrupts going unsatisfied due to a data flood at an input, and human reaction time.
Constraint analysis is designed to identify these limitations to ensure that the program operates within them, and to ensure that all interfaces have been considered for out-of-sequence and erroneous inputs.
Consultive Committee for International Telephony and Telegraphy. ANSI A bus carrying the signals that regulate system operations. See: bus. ISO In programming languages, an abstraction of all possible paths that an execution sequence may take through a program. IEEE A diagram that depicts the set of all possible sequences in which operations may be performed during the execution of a system or program.
Types include box diagram, flowchart, input-process-output chart, state diagram. Contrast with data flow diagram. See: call graph, structure chart. Control Program for Microcomputers. An operating system. A registered trademark of Digital Research.
Hardware that controls peripheral devices such as a disk or display screen. It performs the physical data transfers between main memory and the peripheral device. IEEE Pertaining to a interactive system or mode of operation in which the interaction between the user and the system resembles a human dialog. Contrast with batch. See: interactive, on-line, real time.
IEEE A routine that begins execution at the point at which operation was last suspended, and that is not required to return control to the program or subprogram that called it.
Contrast with subroutine. IEEE Maintenance performed to correct faults in hardware or software. Contrast with adaptive maintenance, perfective maintenance. IEEE The degree to which software is free from faults in its specification, design and coding. The degree to which software, documentation and other items meet specified requirements. The degree to which software, documentation and other items meet user needs and expectations, whether specified or not.
NIST Determining and assessing measures associated with the invocation of program structural elements to determine the adequacy of a test run. Coverage analysis is useful when attempting to execute each statement, branch, path, or iterative structure in a program. Tools that capture this data and provide reports summarizing relevant information have this feature.
See: testing, branch; testing, path; testing, statement. IEEE The sudden and complete failure of a computer system or component. QA A function or an area in a manufacturing process or procedure, the failure of which, or loss of control over, may have an adverse affect on the quality of the finished product and may result in a unacceptable health risk.
IEEE A review conducted to verify that the detailed design of one or more configuration items satisfy specified requirements; to establish the compatibility among the configuration items and other items of equipment, facilities, software, and personnel; to assess risk areas for each configuration item; and, as applicable, to assess the results of producibility analyses, review preliminary hardware product specifications, evaluate preliminary test planning, and evaluate the adequacy of preliminary operation and support documents.
See: preliminary design review, system design review. IEEE The degree of impact that a requirement, module, error, fault, failure, or other item has on the development or operation of a system.
Syn: severity. IEEE Analysis which identifies all software requirements that have safety implications, and assigns a criticality level to each safety-critical requirement based upon the estimated risk.
IEEE An assembler that executes on one computer but generates object code for a different computer. IEEE A compiler that executes on one computer but generates assembly code or object code for a different computer. ANSI A movable, visible mark used to indicate a position of interest on a display surface. A technique for error detection in data communications used to assure a program or data file has been accurately transferred.
The CRC is the result of a calculation on the set of transmitted bits by the transmitter which is appended to the data. At the receiver the calculation is repeated and the results compared to the encoded value.
The calculations are chosen to optimize error detection. Contrast with check summation, parity check. Representations of facts, concepts, or instructions in a manner suitable for communication, interpretation, or processing by humans or by automated means. IEEE 1 Evaluation of the description and intended use of each data item in the software design to ensure the structure and intended use will not result in a hazard.
Data structures are assessed for data dependencies that circumvent isolation, partitioning, data aliasing, and fault containment issues affecting safety, and the control or mitigation of hazards. Usually performed in conjunction with logic analysis. ANSI A bus used to communicate data internally and externally to and from a processing unit or a storage device.
IEEE 1 A collection of the names of all data items used in a software system, together with relevant properties of those items; e. IEEE An exception that occurs when a program attempts to use or access data incorrectly. IEEE A diagram that depicts data sources, data sinks, data storage, and processes performed on data as nodes, and logical flow of data as links between the nodes.
Syn: data flowchart, data flow graph. IEEE The degree to which a collection of data is complete, consistent, and accurate.
Syn: data quality. ANSI A named component of a data element. Usually the smallest component. IEEE A physical or logical relationship among data elements, designed to support specific data manipulation functions. A structured software design technique wherein the architecture of a system is derived from analysis of the structure of the data sets with which the system must deal.
IEEE A diagram that depicts a set of data elements, their attributes, and the logical relationships among them. See: entity-relationship diagram. The process may include format checks, completeness checks, check key tests, reasonableness checks and limit checks. ANSI A collection of interrelated data, often with controlled redundancy, organized according to a schema to serve one or more applications.
The data are stored so that they can be used by different programs without concern for the data structure or organization. A common approach is used to add new data and to modify and retrieve existing data. See: archival database. The degree to which a database is protected from exposure to accidental or malicious alteration or destruction.
Program code statements which can never execute during program operation. Such code can result from poor coding style, or can be an artifact of previous versions or debugging efforts. Dead code can be confusing, and is a potential source of erroneous software changes. See: infeasible path. Validation Center Validation Center brings you all the resources needed for computer system validation. About ProPharma Group ProPharma Group is the global, independent, single-source provider of regulatory and compliance consulting, clinical research solutions, pharmacovigilance, and medical information serving pharmaceutical, biotechnology, and medical device companies.
This is produced by JavaScript and is a form of machine code that runs under the Java virtual environment. The latter is freeware and enables any computer to run Java programs. The person or group that initiates the development process by specifying a problem. A program that translates a complete high level language program into an independent machine code program.
Correction of previously undetected errors during development that is now apparent after installation of the software on the client site. Commercial Off The Shelf software. Unstructured information. A process used in object oriented languages that identifies objects, how they relate to one another and their manipulation. Programmers use this type of language to specify what the problem is rather than how to solve it by writing code. Akin to a dry run where the running of a program is checked without a computer.
Generic description of the personnel involved in developing the software solution. A system that responds to an external event such as mouse click or a key press. An event driven language that is designed to handle external events like interrupts, mouse clicks etc.
Testing the robustness of a program by entering silly data — character data instead of numeric data, excessive values etc. Complete testing of a program under every conceivable condition. Each variable, for example is declared unambiguously by the user so there is much less room for error in running programs Visual basic.
A looping system where information is fed back in to a computer system. The finished program runs to specification and is robust and reliable. A block of code like a procedure but a value is returned when the function is used. A language that utilises the evaluation of expressions rather than the execution of commands. This will detail how the developed program will behave under specified conditions.
The language can be used to program solutions covering a broad range of situations. A language designed to be easily understood by programmers. Allows the program to interact with the outside world. If a variable, for example is not fully declared by the user then it is given default attributes by the Visual Basic language.
The sharing of characteristics between a class of object and a newly created sub class. A form of compiled code that is specifically produced for a target computer.
A program that translates a high level program line by line, which it then tries to execute. An iterative process is one that incorporates feedback and involves an element of repetition.
A diagrammatic design method for small programs that focuses on sequence, selection and iteration. A language designed by Sun Microsystems. A reserved word with a special meaning in a computer language.
A contract set up between client and development team, the details of which are set out in the requirements specification which becomes legally binding should anything go wrong. Part of the compilation process where the source code is tokenised into symbols and stored in the symbol table. A standard algorithm that perform a sequential search on a list of data items. A block of code that automates a repetitive task. A technique involving various notations that enables the design of software to be implemented.
A module library includes code for standard algorithms that can be re-used by programmers. A data item that can be manipulated by a computer system, for example a database record or a file.
A method that centres on objects and the operations that can be performed on them. An object-oriented computer language like Java that uses objects rather than actions and data rather than logic.
An argument of a procedure or function that represents a local variable. The mechanism by which data is passed to and from procedures and the main program. Takes place when a system has to be enhanced in some way e. The ability of a program to run on different machine architectures with different operating systems. The focus is on the problem and how it is to be solved rather than on the hardware on which the program will run.
A document outline of what is to be solved in terms of programming a solution to a given problem. Also known as imperative languages because the programs follow a sequence of steps until they terminate.
A block of code that, when called from within a program will perform a specific action. A section of the development team responsible for the coding, testing, implementation and maintenance of the software. A member of the development team who is responsible for the supervision of the project. A notation combining natural language and code used to represent the detailed logic of a program i. Rapid Application Development.
A programming technique that is iterative in that a procedure or function can call itself. Here the address of the actual parameter is accessed by the formal parameter.
A program is reliable if it runs well and is never brought to a halt by a design flaw. A process that repeats itself a finite number of times or until a certain condition is met.
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