VSAM Interview Questions and Answers - DoAnswers.com

Virtual Storage Access Method (VSAM) is an IBM disk file storage scheme first used in the OS/VS2 operating system and later used throughout the MVS architecture. VSAM comprises four access methods: Key Sequenced Data Set (KSDS), Relative Record Data Set (RRDS), Entry Sequenced Data Set (ESDS) and Linear Data Set (LDS). See record-oriented filesystem. VSAM records can be of fixed or variable length. They are organised in fixed-size blocks called Control Intervals (CIs), and then into larger divisions called Control Areas (CAs). Control Interval sizes are measured in bytes � e.g. 4K � while Control Area sizes are measured in disk tracks or cylinders. Virtual Storage Access Method (VSAM) is an IBM disk file storage scheme first used in the OS/VS2 operating system and later used throughout the MVS architecture. VSAM comprises four access methods: Key Sequenced Data Set (KSDS), Relative Record Data Set (RRDS), Entry Sequenced Data Set (ESDS) and Linear Data Set (LDS). See record-oriented filesystem. VSAM records can be of fixed or variable length. They are organised in fixed-size blocks called Control Intervals (CIs), and then into larger divisions called Control Areas (CAs). Control Interval sizes are measured in bytes � e.g. 4K � while Control Area sizes are measured in disk tracks or cylinders. Virtual Storage Access Method (VSAM) is an IBM disk file storage scheme first used in the OS/VS2 operating system and later used throughout the MVS architecture. VSAM comprises four access methods: Key Sequenced Data Set (KSDS), Relative Record Data Set (RRDS), Entry Sequenced Data Set (ESDS) and Linear Data Set (LDS). See record-oriented filesystem. VSAM records can be of fixed or variable length. They are organised in fixed-size blocks called Control Intervals (CIs), and then into larger divisions called Control Areas (CAs). Control Interval sizes are measured in bytes � e.g. 4K � while Control Area sizes are measured in disk tracks or cylinders.

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When you allocate the vsam cluster at that time you have the option to catlog the dataset using the idcam utility. Apart from this tools like file aid also gives you an option to catalog a vsam dataset.

32. If FSPC(100 100) is specified does it mean that both the control interval and control area will be left empty because 100 % of both CI and ca are specified to be empty?

No, they would not be left empty. one record will be written in each CI and 1 CI will be written for each ca.

33. If you wish to use the REWRITE command haw must the VSAM file be opened?

34. If you wish to use the REWRITE command how should the VSAM file be opened ?

35. In the COBOL SELECT statement for a KSDS what are the three possibilities for ACCESS ?

36. In the COBOL SELECT statement for a KSDS what are the three possibilities for ACCESS?

39. Is a delete operation possible in an ESDS?B. Is rewrite operation possible in ESDS ?

No delete operation is not possible in VSAM ESDS.B. Yes rewrite operation is possible in an ESDS.

40. Is it slower if you access a record through ALT INDEX as compared to Primary INDEX?

Yes. Why? Because the alternate key would first locate the primary key, which in turn locates the actual record. Needs twice the number of I/Os.