VSAM Vs Non-VSAM (for Experienced)
The differences are written by considering VSAM and Non-VSAM file are as below -
- VSAM files can be ESDS, KSDS, LDS, or RRDS.
- Non-VSAM files can be flat files, BSAM files, QSAM files, PS, GDG, or sequential files.
|High-speed data retrieval because of its organized index.||Slow data retrieval because of no organized index.|
|Supports all types of data retrieval (sequential, random, dynamic, linear).||Supports only sequential retrieval.|
|Records can be deleted physically, and the space used by deleted records can be reused for storing newly inserting records without reorganization. This helps for faster retrieving.||Records can be deleted logically but not physically.|
|Supports in batch and online systems.||Supports in the batch system only.|
|Records are in sorted order by default.||Records should get sorted manually before use if required.|
|VSAM files require the utility to create, edit and delete the file.||Non-VSAM files can be created, edited, and deleted using the ISPF facility.|
|Only works with data stored on disk and can't handle data stored on other devices like tapes.||Files can store on both disks and tapes.|
|VSAM uses its own access method to process the data from files.||Non-VSAM files use either use BSAM, QSAM, or BPAM.|
|Supports index and alternate index.||Doesn't support any index.|
|Datasets can be shared across systems and regions.||Datasets stores locally.|
The identical thing is, both VSAM and Non-VSAM files are used in mainframe environment only.
To conclude this, VSAM is a more effective and far better option than non-VSAM files. VSAM files replace the traditional Non-VSAM files everywhere except in report programming.