Introduction to CSE Seminar Topic on VSAM:
VSAM stands for virtual storage access management. It was introduces by IBM and used for data store management. A multiple virtual storage is called MVS which is used as operating system in computers. At the time of operating system installing several memory partitions each of fixed size is set up in the memory. After some time an evolution is come in MVS in which the memory is dynamically allocated to the program as needed but it had some drawbacks for that IBM developed virtual memory which uses three different areas of physical memory. MVS provides service for hardware acceleration that does translation and support ASCII. It has two segments that are concept and facilities, in which a simple introduction is given to the VSAM introducing its components to whom that have not experienced it and second one is access method services in which all function of the VSAM is introduced.
Sometimes VSAM data sets are also called as clusters. These clusters are of various types they are:-
KSDS cluster: – In this the record are placed in the data sets in ascending order and it must contain a key that has unique value and helps to identify the record. Once the key is defined it cannot be deleted or altered.
ESDS Cluster: – In this all the rectors are placed at the end of the data set. In it record cannot be deleted only it can be done inactive. In this the record can be updated without updating the length of the data set.
RRDS cluster: – In this pre formatted slots of fixed lengths are used which has a unique record number. The record number cannot be changed and cannot be deleted. We can insert the new record without disturbing the exiting record and it uses RDF which shows that the slot is occupied or not.
Download CSE Seminar Report on VSAM .