Academic Tutorials



English | French | Portugese | German | Italian
Home Advertise Payments Recommended Websites Interview Questions FAQs
News Source Codes E-Books Downloads Jobs Web Hosting
Chats

Mainframe
Introduction to Mainframe
Mainframe Computers
Mainframe Features
CICS Overview and Functions
CICS Components and Transactions
Introduction to JCL
VSAM Introduction
VSAM Catalogs
VSAM Structure
VSAM Control Interval
VSAM Control Area
JES : Job Entry Subsystem

HTML Tutorials
HTML Tutorial
XHTML Tutorial
CSS Tutorial
TCP/IP Tutorial
CSS 1.0
CSS 2.0
HLML
XML Tutorials
XML Tutorial
XSL Tutorial
XSLT Tutorial
DTD Tutorial
Schema Tutorial
XForms Tutorial
XSL-FO Tutorial
XML DOM Tutorial
XLink Tutorial
XQuery Tutorial
XPath Tutorial
XPointer Tutorial
RDF Tutorial
SOAP Tutorial
WSDL Tutorial
RSS Tutorial
WAP Tutorial
Web Services Tutorial
Browser Scripting
JavaScript Tutorial
VBScript Tutorial
DHTML Tutorial
HTML DOM Tutorial
WMLScript Tutorial
E4X Tutorial
Server Scripting
ASP Tutorial
PERL Tutorial
SQL Tutorial
ADO Tutorial
CVS
Python
Apple Script
PL/SQL Tutorial
SQL Server
PHP
.NET (dotnet)
Microsoft.Net
ASP.Net
.Net Mobile
C# : C Sharp
ADO.NET
VB.NET
VC++
Multimedia
SVG Tutorial
Flash Tutorial
Media Tutorial
SMIL Tutorial
Photoshop Tutorial
Gimp Tutorial
Matlab
Gnuplot Programming
GIF Animation Tutorial
Scientific Visualization Tutorial
Graphics
Web Building
Web Browsers
Web Hosting
W3C Tutorial
Web Building
Web Quality
Web Semantic
Web Careers
Weblogic Tutorial
SEO
Web Site Hosting
Domain Name
Java Tutorials
Java Tutorial
JSP Tutorial
Servlets Tutorial
Struts Tutorial
EJB Tutorial
JMS Tutorial
JMX Tutorial
Eclipse
J2ME
JBOSS
Programming Langauges
C Tutorial
C++ Tutorial
Visual Basic Tutorial
Data Structures Using C
Cobol
Assembly Language
Mainframe
Forth Programming
Lisp Programming
Pascal
Delphi
Fortran
OOPs
Data Warehousing
CGI Programming
Emacs Tutorial
Gnome
ILU
Soft Skills
Communication Skills
Time Management
Project Management
Team Work
Leadership Skills
Corporate Communication
Negotiation Skills
Database Tutorials
Oracle
MySQL
Operating System
BSD
Symbian
Unix
Internet
IP-Masquerading
IPC
MIDI
Software Testing
Testing
Firewalls
SAP Module
ERP
ABAP
Business Warehousing
SAP Basis
Material Management
Sales & Distribution
Human Resource
Netweaver
Customer Relationship Management
Production and Planning
Networking Programming
Corba Tutorial
Networking Tutorial
Microsoft Office
Microsoft Word
Microsoft Outlook
Microsoft PowerPoint
Microsoft Publisher
Microsoft Excel
Microsoft Front Page
Microsoft InfoPath
Microsoft Access
Accounting
Financial Accounting
Managerial Accounting
Network Sites


Introduction to VSAM


Previoushome Next






Introduction to VSAM

Virtual Storage Access Method - VSAM - is a data management system introduced by IBM in the 1970s as part of the OS/VS1 and OS/VS2 operating systems. Although there are still datasets that are best managed with the several other (non-VSAM) data management methods, VSAM is a major component of modern IBM operating systems.

A D V E R T I S E M E N T

Virtual storage access method (VSAM) is an IBM disk file storage access method, first used in the OS/VS2 operating system, later used throughout the Multiple Virtual Storage (MVS) architecture and now in z/OS. Originally a record-oriented filesystem, VSAM comprises four data set organizations: Key Sequenced Data Set (KSDS), Relative Record Data Set (RRDS), Entry Sequenced Data Set (ESDS) and Linear Data Set (LDS). The KSDS, RRDS and ESDS organizations contain records, while the LDS organization (added later to VSAM) simply contains a sequence of bytes with no intrinsic record structure.

IBM uses the term data set in official documentation as a synonym of file, and DASD instead of disk drive. VSAM records can be of fixed or variable length. They are organised in fixed-size blocks called Control Intervals (CIs), and then into larger divisions called Control Areas (CAs). Control Interval sizes are measured in bytes — for example 4 kilobytes — while Control Area sizes are measured in disk tracks or cylinders. Control Intervals are the units of transfer between disk and computer so a read request will read one complete Control Interval. Control Areas are the units of allocation so, when a VSAM data set is defined, an integral number of Control Areas will be allocated.

The Access Method Services utility program IDCAMS is commonly used to manipulate ("delete and define") VSAM data sets.
Custom programs can access VSAM datasets through data definitions (DDs) in Job Control Language (JCL) or in online regions such as in Customer Information Control Systems (CICS).
Both IMS/DB and DB2 are implemented on top of VSAM and use its underlying data structures.

Concepts and Facilities

VSAM was, by several accounts, intended to replace all of the earlier data management systems in use by IBM's operating systems. Conventional (non-VSAM) access methods generally provide only a single type of dataset organization. VSAM provides three:

  • Key Sequenced Data Set (KSDS), where each record is identified for access by specifying its key value - a sequence of characters embedded in each data record which uniquely identify that record from all other records in the dataset. KSDS datasets are similar to Indexed Sequential Access Method (ISAM) datasets, with many of the same characteristics, but also having distinct advantages over ISAM.
  • Entry Sequenced Data Set (ESDS), where each record is identified for access by specifying its physical location - the byte address of the first data byte of each record in relationship to the beginning of the dataset. ESDS datasets are similar to Basic Sequential Access Methid (BSAM) or Queued Sequential Access Method (QSAM) datasets.
  • Relative Record Data Set (RRDS), where each record is identified for access by specifying its record number - the sequence number relative to the first record in the dataset. RRDS datasets are similar to Basic Direct Access Method (BDAM) datasets.

VSAM datasets are frequently referred to as clusters. A KSDS cluster consists of two physical parts, an index component, and a data component. ESDS and RRDS clusters consist of only a single component, the data component.



Be the first one to comment on this page.




  Mainframe eBooks

No eBooks on Mainframe could be found as of now.

 
 Mainframe FAQs
More Links » »
 
 Mainframe Interview Questions
More Links » »
 
 Mainframe Articles
More Links » »
 
 Mainframe News
More Links » »
 
 Mainframe Jobs
More Links » »

Share And Enjoy:These icons link to social bookmarking sites where readers can share and discover new web pages.
  • blinkbits
  • BlinkList
  • blogmarks
  • co.mments
  • connotea
  • del.icio.us
  • De.lirio.us
  • digg
  • Fark
  • feedmelinks
  • Furl
  • LinkaGoGo
  • Ma.gnolia
  • NewsVine
  • Netvouz
  • RawSugar
  • Reddit
  • scuttle
  • Shadows
  • Simpy
  • Smarking
  • Spurl
  • TailRank
  • Wists
  • YahooMyWeb

Previoushome Next

Keywords: mainframe systems,mainframe computers,mainframe features,mainframe server

HTML Quizzes
HTML Quiz
XHTML Quiz
CSS Quiz
TCP/IP Quiz
CSS 1.0 Quiz
CSS 2.0 Quiz
HLML Quiz
XML Quizzes
XML Quiz
XSL Quiz
XSLT Quiz
DTD Quiz
Schema Quiz
XForms Quiz
XSL-FO Quiz
XML DOM Quiz
XLink Quiz
XQuery Quiz
XPath Quiz
XPointer Quiz
RDF Quiz
SOAP Quiz
WSDL Quiz
RSS Quiz
WAP Quiz
Web Services Quiz
Browser Scripting Quizzes
JavaScript Quiz
VBScript Quiz
DHTML Quiz
HTML DOM Quiz
WMLScript Quiz
E4X Quiz
Server Scripting Quizzes
ASP Quiz
PERL Quiz
SQL Quiz
ADO Quiz
CVS Quiz
Python Quiz
Apple Script Quiz
PL/SQL Quiz
SQL Server Quiz
PHP Quiz
.NET (dotnet) Quizzes
Microsoft.Net Quiz
ASP.Net Quiz
.Net Mobile Quiz
C# : C Sharp Quiz
ADO.NET Quiz
VB.NET Quiz
VC++ Quiz
Multimedia Quizzes
SVG Quiz
Flash Quiz
Media Quiz
SMIL Quiz
Photoshop Quiz
Gimp Quiz
Matlab Quiz
Gnuplot Programming Quiz
GIF Animation Quiz
Scientific Visualization Quiz
Graphics Quiz
Web Building Quizzes
Web Browsers Quiz
Web Hosting Quiz
W3C Quiz
Web Building Quiz
Web Quality Quiz
Web Semantic Quiz
Web Careers Quiz
Weblogic Quiz
SEO Quiz
Web Site Hosting Quiz
Domain Name Quiz
Java Quizzes
Java Quiz
JSP Quiz
Servlets Quiz
Struts Quiz
EJB Quiz
JMS Quiz
JMX Quiz
Eclipse Quiz
J2ME Quiz
JBOSS Quiz
Programming Langauges Quizzes
C Quiz
C++ Quiz
Visual Basic Quiz
Data Structures Using C Quiz
Cobol Quiz
Assembly Language Quiz
Mainframe Quiz
Forth Programming Quiz
Lisp Programming Quiz
Pascal Quiz
Delphi Quiz
Fortran Quiz
OOPs Quiz
Data Warehousing Quiz
CGI Programming Quiz
Emacs Quiz
Gnome Quiz
ILU Quiz
Soft Skills Quizzes
Communication Skills Quiz
Time Management Quiz
Project Management Quiz
Team Work Quiz
Leadership Skills Quiz
Corporate Communication Quiz
Negotiation Skills Quiz
Database Quizzes
Oracle Quiz
MySQL Quiz
Operating System Quizzes
BSD Quiz
Symbian Quiz
Unix Quiz
Internet Quiz
IP-Masquerading Quiz
IPC Quiz
MIDI Quiz
Software Testing Quizzes
Testing Quiz
Firewalls Quiz
SAP Module Quizzes
ERP Quiz
ABAP Quiz
Business Warehousing Quiz
SAP Basis Quiz
Material Management Quiz
Sales & Distribution Quiz
Human Resource Quiz
Netweaver Quiz
Customer Relationship Management Quiz
Production and Planning Quiz
Networking Programming Quizzes
Corba Quiz
Networking Quiz
Microsoft Office Quizzes
Microsoft Word Quiz
Microsoft Outlook Quiz
Microsoft PowerPoint Quiz
Microsoft Publisher Quiz
Microsoft Excel Quiz
Microsoft Front Page Quiz
Microsoft InfoPath Quiz
Microsoft Access Quiz
Accounting Quizzes
Financial Accounting Quiz
Managerial Accounting Quiz
Testimonials | Contact Us | Link to Us | Site Map
Copyright ? 2008. Academic Tutorials.com. All rights reserved Privacy Policies | About Us
Our Portals : Academic Tutorials | Best eBooksworld | Beyond Stats | City Details | Interview Questions | Discussions World | Excellent Mobiles | Free Bangalore | Give Me The Code | Gog Logo | Indian Free Ads | Jobs Assist | New Interview Questions | One Stop FAQs | One Stop GATE | One Stop GRE | One Stop IAS | One Stop MBA | One Stop SAP | One Stop Testing | Webhosting in India | Dedicated Server in India | Sirf Dosti | Source Codes World | Tasty Food | Tech Archive | Testing Interview Questions | Tests World | The Galz | Top Masala | Vyom | Vyom eBooks | Vyom International | Vyom Links | Vyoms | Vyom World | Important Websites
Copyright ? 2003-2024 Vyom Technosoft Pvt. Ltd., All Rights Reserved.