Answer Posted / krishna
When there isn't enough space in the control interval VSAM performs a control interval split by moving some records to the free control intervals. If there isn't a free control interval, VSAM performs a control area split by allocating a new control area and moving half of the control intervals to it.
There are two types of splits used extensively in VSAM.
CI-SPLIT Movement of some records from an existing CI to another free CI in the same CA because a record add or update cannot be accommodated in the existing one.
A CI split requires a number of I/O operations and this degrades the performance of the VSAM file. The correct amount of the space will need to be allocated for the CI (internal percentage of free space allocation). This will result in two half-empty CI's instead of one full and one empty CI.
CA-SPLIT Movement of the half of the records in an existing CA to a new CA because a record add or update cannot be accommodated in the existing CA. This results in two approximately half-full CA's instead of one full and one empty CA. This is inefficient because it involves a high level of I/O operations.
Is This Answer Correct ? | 4 Yes | 2 No |
Post New Answer View All Answers
How does control intervals and control areas related to each other?
What are the building blocks used in vsam datasets?
Differentiate between ci split and ca split?
What are the access method services used in vsam?
Explain the index set?
what are s0c1, s0c4, s0c5, s0c7 abends?
is it required that primary key values have to be unique? Do alternate key values have to be unique?
Explain the device independent method to indicate where a record is stored?
What is a vsam dataset?
is it necessary that all versions of the gdg have to be of the same record length?
what is meant by s0c-07 system abend codes?
what do you mean by gdg in vsam?
What is the use of access method services in vsam?
What does the keyranges parameter in define cluster command do?
What is control area?