VSAM Component

A component is an individual part of a VSAM data set. Each component has a name, an entry in the catalog and an entry in the VTOC. The KSDS and VRRDS organizations have data and index components. ESDS, RRDS and LDS organizations only have data components.

There are two types of components, the data component and the index component.

Data component
The data component is the part of a VSAM data set, alternate index, or catalog that contains the data records.

Index component
Using the index, VSAM is able to randomly retrieve a record from the data component when a request is made for a record with a certain key.

A VSAM index can consist of more than one level (balanced tree). Each level contains pointers to the next lower level. Because there are random and sequential types of access VSAM divides the index into two parts: sequence set and index set.


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