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A Client-Based Transaction System To Maintain Data Integrity

IP.com Disclosure Number: IPCOM000128891D
Original Publication Date: 1980-Dec-31
Included in the Prior Art Database: 2005-Sep-20
Document File: 10 page(s) / 37K

Publishing Venue

Software Patent Institute

Related People

William H. Paxton: AUTHOR [+3]

Abstract

This paper describes a technique for maintaining data integrity that can be implemented using capabilities typically found in existing file systems. Integrity is a property of a total collection of data. It cannot be maintained simply by using reliable primitives for reading and writing single units -- the relations between the units are important also. The technique suggested in this paper ensures that data integrity will not be lost as a result of simultaneous access or as a result of crashes at inopportune times. The approach is attractive because of its relative simplicity and its modest demands on the underlying file system. The paper gives a detailed description of how consistent, atomic transactions can be implemented by client processes communicating with one or more file server computers, The discussion covers file structure, basic client operations, crash recovery, and includes an informal correctness proof.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

A Client-Based Transaction System To Maintain Data Integrity

by William H. Paxton

CSL-80-3 MARCH1980

Abstract: This paper describes a technique for maintaining data integrity that can be implemented using capabilities typically found in existing file systems. Integrity is a property of a total collection of data. It cannot be maintained simply by using reliable primitives for reading and writing single units -- the relations between the units are important also. The technique suggested in this paper ensures that data integrity will not be lost as a result of simultaneous access or as a result of crashes at inopportune times. The approach is attractive because of its relative simplicity and its modest demands on the underlying file system. The paper gives a detailed description of how consistent, atomic transactions can be implemented by client processes communicating with one or more file server computers, The discussion covers file structure, basic client operations, crash recovery, and includes an informal correctness proof.

A version of this paper appeared in the Proceedings of the Seventh Symposium on Operating Systems Principles, December 1979.

CR Categories: 4.32, 4.33, 4.35.

Key words and phrases: transactions, file systems, data integrity, reliability, crash recovery.

XEROX PALO ALTO RESEARCH CENTER

3333 Coyote Hill Road / Palo Alto / California 94304

1. Introduction

This paper describes a technique for maintaining data integrity that can be implemented using capabilities typically found in existing file systems. Integrity is a property of a total collection of data. It cannot be maintained simply by using reliable primitives for reading and writing single units -- the relations between the units are important also. The technique described below ensures that data integrity will not be lost as a result of simultaneous access or as a result of crashes at inopportune times.

The environment we have in mind is a collection of computers capable of sending messages to each other over a high bandwidth network [1]. One or more of these computers act as file servers -- they are a shared repository of data for the other machines which are called clients. The client machines issue read or write commands in the form of messages to the particular file server holding the addressed information. The client gets back a response from the server after the command is completed. The response is a message containing the requested information in the case of a read or an acknowledgement in the case of a write.

A transaction is a sequence of reads and writes by some client. Accesses may be made to several files located on different servers. From the standpoint of maintaining data integrity, it is important that the system for carrying out transactions have the following two properties.

Xerpx Palo Alto Research Center Page 1 Dec 31, 1980

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A Client-Based Transaction System T...