Week 3:
Methods of Data Storage
Data storage is the holding of
data in an electromagnetic
form for access
by a computer
processor. There
are two main kinds of storage:
Primary storage is data that
is held in random access memory (RAM) and other memory devices that
are built into computers.
Secondary storage is data that
is stored on external storage devices such as hard disks, tapes,
CD's.
The table below summarizes the
main methods of data storage
Method
|
Description
|
Hard
disks
|
Often
called a disk drive, hard drive or hard disk drive, this method of
data storage stores and provides relatively quick access to large
amounts of data. The information is stored on electromagnetically
charged surfaces called 'platters'.
|
Floppy
disks
|
A
floppy disk is a type of magnetic disk memory which consists of a
flexible disk with a magnetic coating. Almost all floppy disks for
personal computers now have a capacity of 1.44 megabytes. Floppy
disks are readily portable, and are very popular for transferring
software from one PC to another. They are, however, very slow
compared to hard disks and lack storage capacity. Increasingly,
therefore, computer manufacturers are not including floppy disk
drives in the products as a built-in storage option.
|
Tape
storage
|
Tape
is used as an external
storage medium.
It consists of a loop of flexible celluloid-like material that can
store data in the form of electromagnetic charges. A tape drive is
the device that positions, writes from, and reads to the tape. A
tape cartridge is a protectively-encased tape that is portable.
|
Optical
disks
|
An
optical disc is a storage medium that can be written to and read
using a low-powered laser beam. A laser reads these dots, and the
data is converted to an electrical signal, finally converted into
the original data.
|
CD-R
|
Compact
Disc-Recordable ("CD-R") discs
have become a universal data storage medium worldwide. CD-Rs are
becoming increasingly popular for music recording and for file
storage or transfer between personal computers. CDR discs are
write-once media.
This means that - once used -they cannot be erased or re-recorded
upon. CD-R discs can be played back in any audio CD player or
CD-ROM drive, as well as many DVD
players
and drives.
|
CD-RW
|
Compact
Disc-Rewritable (CD-RW) disks are rewritable and can be erased and
re-recorded upon over and over again. CD-RW discs can only be used
on CD players, CD-ROM drives, and DVD players and drives that are
CD-RW playback-compatible.
|
DVD
|
A
DVD (Digital Versatile Disc or Digital Video Disc) is a high
density optical disc with large capacity for storage of data,
pictures and sound. The capacity capacity is 4.7 GB for single
sided, single layer DVD disc - which is approximately 7 times
larger than that of a compact disc.
|
INFORMATION NEEDS AND
INFORMATION SEEKING BEHAVIOUR
What is an information need?
According to Wikipedia,
information need is an individual or group’s desire to locate and
obtain information to satisfy a conscious or unconscious need. The
“information” and “need” in “information need” are
inseparable. Needs and interest call forth information.
The concept of information
needs was coined by an American information scientist, Robert S.
Taylor in his article “ The process of asking questions”
published in American Documentation now Journal of the American
Society of Information Science and Technology.
In his paper, Taylor attempted
to describe how an inquirer obtains an answer from an information
system, by performing the process consciously or unconsciously. Also
he studied the reciprocal influence between the inquirer and a given
system.
According to Taylor,
Information needs have four levels:
- Conscious and unconscious need for information not existing in the remembered experience of the investigator. It is the actual but unexpressed need for information.
- The conscious mental description of an ill-defined area of indecision. In this level, the inquirer might discuss with somebody in a particular field to get an answer.
- At the researcher’s level, he forms a rational statement of his question. This statement is a rational and unambiguous description of the inquirer’s doubt.
- The question as presented to the information system.
The need for information in
these modern times cannot be overemphasized. To thrive in this modern
era, one needs a variety of information, no matter how one is versed
in a field or profession. Information plays a significant role in our
professional and personal lives. People need information to work
properly in their fields. For instance information needs and
information seeking behavior of academics have been a popular area of
research for the information scientist (Majid and Kassim, 2000).
Zhang (1998) stresses that a thorough understanding of users’
information needs and information seeking behavior is fundamental to
the provision of successful information service.
INFORMATION SEEKING
BEHAVIOUR
Information seeking behavior
result from the recognition of a need (s) perceived by the user. It
is a conscious attempt on the part of the user in satisfying a
particular type of need. The behavior elicited by the user is
tailored towards the satisfaction of that particular need. The
behavior may take several forms: For example the user may make
demands on formal systems that are customarily defined as information
systems; such as libraries, On-line services, information centers or
upon systems which perform information and non-information functions.
On the other hand, the user may seek information from other people
rather from systems.
INFORMATION SYSTEMS
DEVELOPMENT
An information system is
defined as a means of providing information in such a way that it
will be most useful to the persons for whom it is intended (Tiamiyu,
2003). In other words, an information system comprises of
complementary activities that are performed towards a common
objectives of facilitating information flow within a community,
department or unit within an organization.
Information systems are
usually established to facilitate such activities as the creation,
organization, storage, retrieval, transfer, computation and use of
data. Such activities require material and human resources with a
technology to create and process data into more valuable data and
information.
Information systems vary
greatly in their objectives, scope and complexity. For instance in an
organization, an information system comprises of smaller
interconnecting sub-systems that serve the needs of particular
departments, units, workgroups or personnel in the organization. An
organization provides the forum where human, paper-based (manual),
computerized and other information systems overlap and interface with
one another across departments and units.
The various departments and
units that can make up an organizational information system include
the following:
- Central administration department including strategic planning, finance, personnel and public relations.
- Production department
- Sales /marketing, purchasing and inventory department.
- Research and development department.
Each of these units has
overlapping functions whereby the output of one serves as an input to
another i.e they interface with one another.
COMPONENTS OF AN
INFORMATION SYSTEM
An information system is
composed of all the components that collect, manipulate and
disseminate data or information. It includes hardware, software,
people, communication systems, procedures and data itself. The
activities of an information system centre on inputting data,
processing of data into information, storage of data and information
and the production of output for the end users such as Management
report.
The components of an
information system are outlined below:
- Human Resources: This constitutes the organizational personnel who act as decision makers, operational level staff, data collectors, computer system operators and managers.
- Socio-organizational framework: It comprises policies, procedures and social networks governing the relationships among personnel; between personnel and the organization; between personnel and their work; between personnel and information; and between personnel and data processing equipment.
- Computer and telecommunication hardware: Computer hardware and telecommunication facilities are needed to facilitate the inputting, processing and storage of data. It could also aid the transfer of data from one source to another.
- Computer software: These are sets of instructions that are used to determine the type of processing to be performed on data and information. For instance there are various applications software which can be utilized for processing data and information.
- Data and information: These are potentially informative symbols recorded as words, numbers or graphs in memos, forms, data sheets, tables, computer files, reports etc.
TYPES OF INFORMATION
SYSTEMS
The three major types of
information systems are:
Others are:
- Executive information systems
- Expert system
- Office information system
- Document or record management system
- Transaction Processing Systems
TPS processes business
transaction of the organization. Transaction can be any activity of
the organization. Transactions differ from organization to
organization. For example, take a railway reservation system.
Booking, canceling, etc are all transactions. Any query made to it is
a transaction. However, there are some transactions, which are common
to almost all organizations. Like employee new employee, maintaining
their leave status, maintaining employees accounts, etc.
Transaction processing systems
provide speed and accuracy, and can be programmed to follow routines
functions of the organization.
The transaction processing
system attends to the daily or short term information needs of the
organization such as attendance records of the employees. This kind
of information is required at the operational level for carrying out
the day-to-day operational activities. Due to its capabilities to
provide information for processing transaction of the organization,
the information system is known as Transaction Processing System or
Data Processing System. Some examples of information provided by such
systems are processing of orders, posting of entries in bank,
evaluating overdue purchaser orders etc.
Management information system
collates, captures data from low level management and summarizes it
as a report for management. It produces the output as a report.
These
systems assist lower management in problem solving and making
decisions. They use the results of transaction processing and some
other information also. It is a set of information processing
functions. It handles queries as quickly as they arrive. An important
element of MIS is database.
A
database is a non-redundant collection of interrelated data items
that can be processed through application programs and available to
many users.
The type of information
required by the middle management is known as managerial information.
The information required at this level is used for making short term
decisions and plans for the organization. Information like sales
analysis for the past quarter or yearly production details etc. fall
under this category. Management information system (MIS) caters for
the information needs of the organization. Due to its capabilities to
fulfill the managerial information needs of the organization,
Management Information Systems have become a necessity for all big
organizations. And due to its vastness, most of the big organizations
have separate MIS departments to look into the related issues and
proper functioning of the system.
- Decision Support Systems
These systems assist higher
management to make long term decisions. These
type of systems handle unstructured or semi structured decisions. A
decision is considered unstructured if there are no clear procedures
for making the decision and if not all the factors to be considered
in the decision can be readily identified in advance.
A computerized decision
support system deals with calculations, forecasts, prediction,
optimization and simulation in order to support Top Management
decisions. It goes beyond providing information to support decision
making. A special software is needed to do the analysis.
The information provided by
DSS is of strategic value; hence it is used by Management for
decision making. For example the trends in revenues earned by the
organization are required by the top management for setting the
policies of the organization. This information is not required by the
lower levels in the organization.
- EXECUTIVE INFORMATION SYSTEM
This is an information system
designed for executives in an organization. They help in strategic
decision making. EIS depends on both the MIS and the environment for
information. The information can be tit bits not necessarily
voluminous. Information of this nature can be about competitors,
profitability and other alerting sources.
EIS selectively disseminates
information to the top Management of an organization. The information
obtained either from within or outside the organization are of
strategic importance, and are passed to them real time with no
complex analysis. The EIS evaluates the information coming from
outside or within the organization to prevent information overload.
- EXPERT SYSTEM : Evaluating and taking decisions on the part of the executives has led to the development of the expert system. Expert system is designed to make recommendations based on the data that had been fed into it. It simulates a human expert in a particular field in evaluating data and recommending actions to be taken.
- OFFICE INFORMATION SYSTEM: This comprises of seamless integration of computing and telecommunication office technologies in the office environment within an organization. The OIS is designed to reduce the need for paperwork in an organization, reducing the need for multiple capture of data and making the office environment more pleasurable for office workers. These technologies facilitate speedy and efficient storage, retrieval, delivery and processing of data, documents and messages in the office.
- DOCUMENT OR RECORDS INFORMATION SYSTEM: This type of system is designed to manage the corporate records of an organization. The computer can be used to manage the records. There are various ways of managing organizational records. These include:
- Extracting information from a document and keyed it into a computer data file for storage.
- Scan the document and later stored on a data file.
- The document or record can be stored on a CD-ROM due to its durability and longevity.
Figure
1.2 - Relation of
information systems to levels of organization
INFORMATION SYSTEMS
METHODOLOGIES
According to Avison and
Fitzgerald (1995) an information system development methodology is
defined as a system of procedures, techniques, tools and
documentation which help system developers to implement a new system.
There is no standard
methodology to be adopted for every problem situation in system
development. The main problem for most system analyst is which
methodology or which combination of methodologies to adopt in solving
a particular problem.
The structured approach to
systems development or the traditional approach is an orderly step-
by step approach to performing a sequence of activities in the
process of developing any type of information. Another name for it is
the System Design Life Cycle (SDLC).
The sequence of system
development as identified by Jeffery and Lawrence, 1984) are
mentioned below: This can be applied from manual to computerized
system.
- PROBLEM DEFINITION AND REQUIREMENT SPECIFICATION: This is the stage during which problems or deficiencies associated with an existing information system are articulated. The problem of the old system will determine the requirement to be met by the proposed system.
- SYSTEM ANALYSIS AND FEASIBILITY STUDY: The focus is on Analyzing the existing system in detailed and proposing alternative system that could meet the requirement of the new system. The alternatives systems are analyzed to such a depth as to determining which of the alternatives are feasible and cost effective.
- SYSTEM DESIGN: The detailed physical and logical design of the proposed new system is performed at this stage. The logical design focuses on what the new system will be doing with data, complete description of data and data flows in terms of input, processing and output data. The physical design provides a complete description of all input and output format, data files, databases, forms, data processing equipment, personnel, software specification, system security, control and operational requirement.
- PROGRAMMING: The software specifications are coded by programmers into a computer program using a particular programming language. The program is comprehensively tested to remove errors. Complete documentation of the computer program and user manual are produced. In the alternative, a ready made software can be purchased that would meet the data processing requirement of the proposed system.
- IMPLEMENTATION: The objective of this stage is to provide a working system for the organization by developing an organizational environment in which the system will operate. The task performed at this stage involves installing and testing the complete system within the environment of the organization, site preparation, purchase and installation of equipment and software, training of operators and users of the system, conversion of the existing data into formats that can be used by the system. The old system is run concurrently with the new system before final change over to the new system.
- POST IMPLEMENTATION EVALUATION This is done prior to and after complete change over from the old to the new system. The purpose of this review is to ascertain whether the new system is meeting the requirement as originally set. This evaluation will provide a feedback to the system designer as to the correctness of their analysis and design, and might instigate a new system development.
INFORMATION SYSTEMS CAREERS
Information systems have
various career prospects. The careers allows for multi- specialty. A
detailed description of each of the careers is listed below:
- SYSTEM ANALYST: A system Analyst is a person who selects and configures computer information systems for an Organization or business. The system Analyst job begins with determining the understanding the general objectives of the Organization, the system and user requirements. Once the system Analyst has determined the general and specific needs of the system, he can choose an appropriate system that will accomplish the goals of the business.
- SYSTEM DESIGNER: A system designer is a person who designs, develops and implements the clearly defined information requirement of the new system. This entails planning, designing information systems that integrate hardware, software and communication technologies. Systems designer are usually central to the development and installation of new IT system, which are run in parallel with the old system until all the bugs in the new system are found and resolved.
- SYSTEM PROGRAMMER: In an IT Organization, a system programmer plays a central role. He installs, customizes and maintains the operating system. He installs or upgrades products that run on the system. Other tasks performed by the system programmer include the following: Planning hardware and software system upgrades and changes in configuration, Training system operators, Performing installation specific customization task, Debugging problems with system software and System wide performance tuning to meet required levels of service.
- DATABASE SYSTEM ADMINISTRATOR (DBA) The DBA maintains the system software environment for business purposes. He does the day-to-day maintenance of the system to keep them running smoothly. The DBA also ensures the integrity of, and efficient access to data that is stored in the database. Other tasks performed by the DBA include: installing software, adding and deleting users and maintaining user profiles, managing storage devices and printers, managing networks, connectivity and system performance.
- INFORMATION TECHNOLOGIST: Information technologists operate, maintain and control information systems and equipment. In some organizations they are referred to as information support personnel or communication support specialist.
- INFORMATION MANAGERS: Information Managers plan, develop coordinate and control information systems, human and material resources needed for the systems and processing. The main role of an information Manager is to coordinate activities, sub systems and services under him. They are also called Director of information services.
