Several new disk arrays have recently been proposed in which the parity groupings are uniformly distributed throughout the array so that the extra workload created by a disk failure can be evenly shared by all the surviving disks, resulting in the best possible degraded mode performance. Many arrays now also put in multiple spare disks so that expensive service calls can be deferred. Furthermore, in a new sparing scheme called distributed sparing, the spare spaces are actually distributed throughout the array. This means after a rebuild the new array will be logically different from the original array. The authors present an algorithm for constructing and maintaining arrays with distributed sparing so that repeated uniform parity group distribution is achieved with each successive failure.>

Disk arrays are increasingly being used in distributed computing systems, as the vehicle for providing reliable and high performance data storage. When a disk in a RAID-5 fails, data in that failed disk can still be made available through parity reconstruction by reading from the other disks. However, this poses an increased burden on the surviving disks, and if consideration is not given to this failure consequence, then the performance of the system may degrade to an unacceptable level. This paper describes techniques that will enable the disk array to maintain good performance in the event of a disk failure. After a failed disk has been repaired, its content must be reconstructed from all the associated parity groups. In RAID-5, this must be a single thread sequential process. With the techniques introduced in this paper, it is shown how this sequential process can now be broken down into multiple parallel processes distributed throughout the array, thus shortening the reconstruction time. While the techniques introduced in this paper are applied to disk arrays, they may potentially have general applications in other areas of distributed computing.>

Information networks in which workstations access central data collections primarily to extract information are a growing application segment. When a workstation is likely to use an item more than once it may be economical to retain a copy locally. We describe how to propagate updates for an arbitrary relationship between the source database and cached items when the network connection is intermittent, unreliable, and/or slow.

In many systems for pattern recognition or automatic decision making, decisions are based on the value of a discriminant function, a real-valued function of several observed or measured quantities. The design of such a system requires the selection of a good discriminant function, according to some particular performance criterion. In this paper, the problem of finding the best linear discriminant function for several different performance criteria is presented, and a powerful method of finding such linear discriminant functions is described. The problems to which this method may be applicable are summarized in a theorem; the problems include several involving the performance criteria of Bayes, Fisher, Kullback, and others, and many involving multidimensional probability density functions other than the usual normal functions.

An algorithm is developed for synthesizing networks which realize Boolean switching functions through the use of a minimum number of threshold logic elements. A switching function is represented by a matrix and the algorithm is based on the principle that the removal of the positive linear dependences from the rows of this matrix results in a linearly separable function. The positive linear dependences are removed by adding columns to the matrix, each column representing the output of a threshold logic element in the network. The added columns in effect transform a nonseparable function into a sparable function a higher dimensional space. The algorithm is illustrated with examples of the synthesis of both single and multiple output networks. The technique is not restricted to completely specified functions.

article Free Access Share on Feature Word Construction for Use with Pattern Recognition Algorithms: An Experimental Study Authors: R. L. Mattson Stanford University and Lockheed Missiles and Space Company Stanford University and Lockheed Missiles and Space CompanyView Profile , O. Firschein Lockheed Missiles and Space Company, Palo Alto, California Lockheed Missiles and Space Company, Palo Alto, CaliforniaView Profile Authors Info & Claims Journal of the ACMVolume 10Issue 4Oct. 1963 pp 458–477https://doi.org/10.1145/321186.321189Published:01 October 1963Publication History 1citation504DownloadsMetricsTotal Citations1Total Downloads504Last 12 Months7Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my Alerts New Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

This paper discusses a class of pattern-recognition decision-making procedures which can be efficiently mechanized by a network of linear threshold devices. A theoretical discussion of four decision techniques (which are members of the above-mentione class) is augmented by an experimental program which investigates questions not amenable to analysis.

In this paper, the pattern recognition problem is considered to be composed of two subproblems. The first subproblem is one of abstracting significant features or characteristics from the patterns being dealt with, while the second subproblem is concerned with identifying the pattern which gave rise to a particular set of features (i. e., a decision-making problem). The decision-making system to be discussed is a special purpose digital computer, which simulates a network of threshold elements designed to correctly identify a preselected set of "typical" patterns. In addition to describing the design procedures, methods of feature extraction, and the hardware employed, the resuits of experiments involving several thousand handwritten characters will also be presented.