Pre-SMS Data Set Block Linking DEBs to DSSBs for IPL I/O Statistics
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Solution Overview
Problem
The system is unable to capture and report I/O statistics for data sets accessed during initialization (IPL) because the Storage Management Subsystem's address space is not ready, and basic Data Extent Blocks (DEBs) do not include the address of Data Set Statistics Blocks (DSSBs), preventing the accumulation of response time metrics for these data sets.
Innovation Solution
A new structure, Pre-SMS Data Set Block, is defined to link basic DEBs with DSSBs during initialization, allowing I/O statistics to be saved in DSSBs without modifying the extended DEB, enabling the collection and reporting of I/O response time metrics for data sets opened during IPL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If basic Data Extent Blocks (DEBs) are used during system initialization, then the system can access data sets during IPL, but I/O statistics cannot be captured and reported because DEBs do not include addresses of Data Set Statistics Blocks (DSSBs)
Solution Approach 1:
The patent implements a nested structure where a new Pre-SMS Data Set Block is inserted between the basic DEB and the DSSB. This intermediate block contains a pointer to the DSSB, creating a chained list structure that allows I/O statistics to be captured without modifying the original basic DEB structure. The nesting enables statistics collection while preserving the existing simple DEB format.
Solution Approach 2:
The Pre-SMS Data Set Block acts as an intermediary between the basic DEB and the DSSB. It provides the missing link by containing a pointer to the DSSB, allowing the system to associate I/O statistics with data sets opened during initialization without requiring changes to the basic DEB structure or the DSSB structure.
2Reliability
If the Storage Management Subsystem's address space is not ready during initialization, then system initialization can proceed, but I/O statistics cannot be stored because the address space for statistics blocks is unavailable
Solution Approach 1:
The patent creates the Pre-SMS Data Set Block during system initialization before the Storage Management Subsystem's address space is fully ready. This preliminary action establishes the basic data structure and pointer relationships early in the initialization process, allowing the system to proceed with initialization while setting up the framework for future statistics collection once the address space becomes available.
Solution Approach 2:
The patent separates the data set management functionality into distinct segments: the basic DEB for data set identification, the new Pre-SMS Data Set Block for linking during initialization, and the DSSB for statistics storage. This segmentation allows each component to be initialized and managed independently, enabling system initialization to proceed while I/O statistics infrastructure is being prepared.
Data Source
AI summary
A computer-implemented method of storing I/O statistics of a data set during initialization of a system. The computer-implemented method includes receiving during system initialization, by a processor, a data extent block associated with the data set. Next, the method identifies during system initialization, by the processor, a data set statistics block linked to an identified data set block, and stores, by the processor, the I/O statistics in the data set statistics block.