Question

What are the various types of VSAM files?

Answer 1

VSAM data sets can be classified into the following types:

1. RRDS (Relative-record data set): It contains records ordered by relative record number and is accessible via this number. In RRDS datasets, records are stored in slots of a fixed length.
2. ESDS (Entry-sequenced data set): It contains records in the order of entry or in sequential order and is accessible only via relative byte addresses. ESDSs are similar to sequential data sets. Records in ESDS datasets can have variable or fixed lengths.
3. KSDS (Key-sequenced data set): It contains records ordered by key field and is accessible via key-value or relative byte address. Records in KSDS dataset can be of fixed length or variable length.
4. LDS (Linear data set): It is composed of an unstructured data set whose Control Interval (CI) size is multiple of 4K.