Allocating secondary space for history files

For PDSE history files in particular, it is important to allocate the data set with secondary space. Failure to do so might result in out-of-space conditions with subsequent loss of data.

Fault Analyzer normally auto-manages a PDSE history file within the logical history file size: the allocated size that is established the first time the history file reaches the minimum number of fault entries. (See AUTO-managed PDSE history files.) However, primarily due to the concurrent update capability of a PDSE, it is not always possible to guarantee the availability of free space as new fault entries are written. Therefore, it is crucial for Fault Analyzer to have the ability to extend the history file with secondary space in situations where the expected space is not available.

Because of the logical history file size concept employed by Fault Analyzer, the used size of the history file is automatically reverted to the original size when the next update occurs, and the secondary extent that was allocated is left unused until perhaps a similar situation that requires extra space occurs again. The important thing to note is that the history file does not continue to grow indefinitely.

When the IDIS subsystem detects a PDSE history file without secondary space, it issues message IDI0191W.