Posted On: Mar 25, 2019
Difference between VSAM AND NON-VSAM FILES
Storage is an important aspect in today’s world and its use is known to almost every user, but ever wondered what mechanisms work in the background which allows us to access data from storage. This is a very broad topic for discussion and requires a deep understanding of computer architecture. Here we will try to create a separation between VSAM and Non-VSAM files.
VSAM stands for Virtual Storage Access Method which is a product of tech giant IBM’s Direct Access Storage Device file storage method which in simple terms is a secondary storage device in which every single physical record has a specific location and address. VSAM is basically a chunk made up of four data sets organizations which are Key Sequence Data Set, Relative Record Data Set, Entry Sequenced Data Set, and Linear Data Set. Data sets are those computer files that keep a note of record organization. It is important to note that IBM uses data set as a fancy name in place of files in its official documentation in case you come around this term and wonder what does it refer to. Generally, the point that counts in favor of VSAM files when compared to other flat files is that it can read records randomly on a key.
There exist another set of files termed Non-VSAM files, these data sets are a collection of fixed length or variable length records which are grouped into blocks. There are few different types of Non VSAM files or data sets like Sequential Data Set which contains data that are in physical order, Partition Data Set which have a directory of sequentially organized members each one of them may contain a program or data and there is this Partition Data Set Extended which completes the list of types of Non-VSAM files. So it is another form of data management that Operating Systems use in order to store data.
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