VSAM stands for Virtual Storage Access Method. It is a data set type and an easy, fast, secured data access method. There are four kinds of VSAM. First, the most common one is Key Sequence Data Set (KSDS). It provides random access thanks to indexed data. IMS uses KDSDs. The second kind, Entry Sequence Data Set (ESDS) keeps non-indexed records in sequential order. It is used by IMS, DB2, and z/OS UNIX. Third kind, Relative Record Data Set (RRDS) uses numbered record. This kind is rare. The last one is Linear Data Set (LDS) but it will never appear in modernization projects.
VSAM in Blu Insights
A good understanding of the VSAM design is a prerequisite for a successful modernization. In particular, to know if datasets are a key-point of the project or not and if the client has provided all needed files.
By aggregating information from multiple files, the dependency analysis detects and differentiates VSAM datasets. The CSD file includes dataset declarations and JCL Control Cards specifying the VSAM kind. This kind is determined from properties (KSDS: indexed, ESDS: nonindexed, RRDS: numbered, LDS: linear). With this new feature, the customer can filter the VSAM nodes to find their parents and create the Blusam entities easily. 📊
For example, in CardDemo project, we have detected that 15 out of the 17 found datasets are of type VSAM KSDS. 🎉
The remaining datasets are indirect use of other dataset.
Have a productive day 🚀