In the late 1970’s IBM introduced VSAM: Virtual Sequential Access as its new access method; it replaced ISAM and BDAM. VSAM added functionality, device independence, and improved performance. It was also easier to use. There have been numerous improvements made to VSAM and it is still integral  mainframe system software. VSAM is used extensively in the CICS Transaction Server environment to provide recoverability, data locking, and integrity to source data. Sharing of VSAM data among CICS regions is done with VSAM RLS: Record-Level Sharing; this adds record caching and record locking. Logging and commit processing remains the responsibility of CICS. This means that sharing of VSAM data outside a CICS environment will be restricted.

VSAM has been the workhorse access method for IBM’s z/OS and z/VSE evolutionary operating system's and system software products: IMS, CICS, and DB2. Although the role of VSAM and its relative importance has changed with the emergence of DB2 and web enablement technologies, a knowledge of VSAM is important for optimizing performance and balancing the processing of input/output.

VSAM now uses some of the newer hardware technology to improve performance. In a multi-extent, multi-volume VSAM dataset processed in sequential access, processing does not allow for any type of parallelism for I/O operations among the volumes. This means that when an I/O operation is executed for an extent in a volume, no other I/O activity from the same task or same dataset is scheduled to the other volumes. In a situation where I/O is the major bottleneck, and there are available resources in the channel subsystem and controllers, it is a waste of these resources.

Data striping addresses this sequential access performance problem by adding two modifications to the traditional data organization:

• The records are not placed in key ranges along the volumes; instead they are organized in stripes.
  
• Parallel I/O operations, in the form of control intervals are scheduled to sequential stripes on different volumes.

Enhancements have been made to VSAM with the IBM z/OS V1.10 operating system. The VSAM CA Control Area Reclaim capability provides applications which use VSAM KSDS key-sequenced datasets with improved availability through minimizing outages required for data defragmentation and reorganization. Disk space utilization also is better. CETi Technology Partners are evaluating IBM product announcements regarding performance, which have been reported to be as high as a 44% improvement for VSAM-based workloads.

When information technology professionals leave a SYS-ED VSAM course, they have the skeleton programs, documentation, training aids, and supervised hands-on experience to efficiently code and maintain programs back on the job. Case and point, we encourage clients to provide us with listcats from their production systems prior to attending a class. We analyze and interpret that information and teach the concepts and techniques required to make VSAM performance optimization a reality.

The value added service to a SYS-ED VSAM course is the educational consultancy we can provide. Case and point, if your organization outsourced its CICS and VSAM coding and program maintenance to consulting companies in the 1980’s, it more than likely was SYS-ED which trained the consultants who did the actual design and coding!

Qualifying and Delivering Mainframe Training Services
CICS	COBOL
DB2 UDB	VSAM Performance and Tuning

IBM's information agenda is built on its proprietary operating systems and system software. Its foundation is to simplify, collaborate, reuse, and standardize. SYS-ED's mainframe course offerings, training programs, and software specific websites have been designed to add value-added service to this strategy and IBM's cloud computing initiatives.

1- Delivery of content through multiple delivery medium as part of a collaborative environment for integrating data at a business level.

2- Student hand-outs, reference guides, and validation assessment for training human resources that leverage existing investments in software infrastructure.

3- Application development accelerators in the form of industry and client-specific training aids, examples, templates, and data modeling.

4- Support services in the form of technology updates, knowledge base, answers to questions, and tailored documentation in hybrid and interrelated information technology.

The VSAM courseware and training aids that we provide as part of our instructor-led courses are highly respected. The content and diagrams reflect a purposeful examination of program logic, access methods services, and sample programs which have been validated on consulting projects. SYS-ED's VSAM courseware is updated with information from FAQ's frequently asked questions, technology updates, and CETi knowledge base. Given the scarcity of up to date industry standard VSAM text books, our courseware serves a valuable function as a reference manual.

Upon completion of a instructor-led course at the client location, it is standard policy to organize content for future utilization in a web-based training infrastructure.

Longstanding Experience in
Information Technology