Types of VSAM datasets

There are three main types of VSAM datasets:

1. KSDS (Key Sequenced Data Set): KSDS is a VSAM dataset type where records are stored in ascending order of a key field. Each record in a KSDS dataset has a unique key.
2. RRDS (Relative Record Data Set): RRDS is a VSAM dataset type where records are stored in relative record numbers, allowing for direct access to records based on their position within the dataset.
3. ESDS (Entry Sequenced Data Set): ESDS is a VSAM dataset type where records are stored in the order they are written to the dataset. Records are accessed sequentially in the order they were written.

Each of these VSAM dataset types has specific characteristics and is defined based on the requirements of the application and the access patterns of the data.