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Backing up a stand-alone system

Library Systems Newsletter [July 1981]


The typical stand-alone system is 95 to 98 percent reliable. During normal operations all transactions can be conducted. From 2 to 5 percent of the tine one or more essential components will not be functioning and a library will have to resort to some type of back up system. Virtually all of the back up devices for stand-alone systems acquired to date are intended to keep circulation operations going during the time that an automated system is down. In the case of a library open 60 hours per week, that can be more than three hours each week during the time that patrons are using the library.

All of the libraries contacted had purchased an electronic back up system for the purpose of recording transactions while their primary system was not available. Usually the choice was one of three types: A tape cassette unit, a bubble memory device, or a portable terminal. The first appears to be in the most widespread use, but it has also been the source of the most bitter complaints.

The concept of a tape cassette unit is simply one of recording each transaction at a terminal on a cassette tape for later entry into the computer, rather than transmitting the information to the computer immediately. Several cassettes may be filled during a protracted period of down tune, thus subsequently requiring several hours to load the data into the computer. This "batch loading" requires sound procedures so that the transactions are maintained in the proper sequence. Many of the complaints we identified involved inadequate procedures for removing, marking, collecting and loading data cassettes. When cassettes are mixed up and a tape with a charge for an item is loaded after a tape containing the subsequent discharge, there will be patron complaints about incorrect notices, etc. But even some libraries with sound procedures reported difficulties. Several libraries said that they had lost data during the back up period. A pattern began to emerge after about six calls. All of the libraries with serious problems had arranged for a switch mechanism to be installed to facilitate the implementation of the cassette back up system. Without the switch the connection of the cassette unit can be cumbersome. Not all staff do it well and no one likes to do it with several impatient patrons watching. Unfortunately, the more convenient switches have not been reliable. Several libraries have found blank tapes when they subsequently sought to load the data.

A few libraries have replaced the relatively inexpensive tape units with TI (Texas Instrument) bubble memories. They appear to be more reliable than the tape cassette, but they are twice as expensive. They also have very limited storage capacities. Most of those in use can accommodate only 20,000 (20KB) characters of information, although some are available with an 80KB capacity. Such a terminal is. therefore, suitable for a short period, but not for several hours or days. Every one of the libraries we contacted had been down for at least one full day during the previous three months and three had been down for over one week.

Recently more libraries have selected a portable terminal, While they are expensive ($5,000 and up), they can also be used for conducting periodic electronic inventories of the library and are suitable for bookmobile use. They are extraordinarily sensitive, however. They cannot be casually dropped on a table and should not be placed on top of a dusty book case, or kept on a "hold" (reserves) shelf under the counter. The repair frequency of the portable terminals was the most frequent complaint we encountered, especially from CLSI customers. Several libraries complained that DataPhase had been very slow to develop the software for loading data from the portable terminals. One library bought ten portable units. but had to store them for several months and use a manual back up system while the software development, which it thought was already taken care of, was completed--it has now been.

No one appears to be happy with any of these back up devices, but among the libraries which have very carefully drawn back up procedures and which treat the equipment as delicate electronic equipment (which it is) the portable terminal users appear to be least annoyed. The libraries which have reverted to manual data collection means can best be described as resigned. They spend hours keying in data after the automated system is restarted, but they do not lose any data.

Several libraries have concluded that the best way to back up a computer system is to add a second CPU (Central Processing Unit). This usually adds no more than 10 percent to the total cost of a system. While thus is a reasonable decision, it cannot be the whole solution because the computer itself is usually the most reliable component in the system. In a system that is 96 percent reliable, the CPU is usually 99 percent reliable. It is the electro-mechanical devices which fail more often, among them the disk drives on which the records are stored.

The Brigham Young University Library, a CLSI user, was not satisfied with the available options and chose to develop its own. It purchased an APPLE Microcomputer and developed the software to collect transactions while the circulation system was down. It has now established a separate company called computer Translation Incorporated to market the CTI back up system. The full hardware and software package costs less than a single portable terminal, yet can be used to back up several terminals. The data is stored on diskettes, which can be replaced when full. The company is willing to consider developing the software for systems other than CLSI, but its decision is dependent on the sales prospects being good enough to warrant the effort [Contact Computer Translations, Inc., Box 7004 University Station, Provo, UT 84602).

One vendor observed: "Back up is not very important to libraries buying a system. It is only after the first extended period of down-time that we hear much about it. Even before we do something, the libraries have developed manual back up." Were libraries to place more emphasis on back up in their specifications, the priorities of vendors would probably change. In the short-term, it might lead to more reliable back up systems for recording transactions. In the longer-term, it might result in the development of microprocessor-configured back up systems with the capability of storing files of delinquent borrowers and lists of holds and other exceptions, rather than just united transaction data.

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Publication Year:1981
Type of Material:Article
Language English
Published in: Library Systems Newsletter
Publication Info:Volume 1 Number 01
Issue:July 1981
Page(s):3-4
Publisher:American Library Association
Place of Publication:Chicago, IL
Notes:Howard S. White, Editor-in-Chief; Richard W. Boss, Contributing Editor
Subject: Integrated library sytsems -- backup methods
ISSN:0277-0288
Record Number:3673
Last Update:2021-11-17 12:27:41
Date Created:0000-00-00 00:00:00