Browse Prior Art Database

Integrity of System Images for a Save/Restore IPL Function in an Operating System

IP.com Disclosure Number: IPCOM000041342D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Duvall, KA: AUTHOR [+2]

Abstract

To improve the time it takes to establish a particular system to the point where productive program execution can take place on initial program loads (IPL) other than the first, the first IPL is allowed to proceed to a point where the initialization of most of the time-consuming components is completed and the system image (contents of registers, storage, etc.) at that point is saved. A subsequent IPL using such a system image as a starting point established by restoring that image can be completed very quickly, but the integrity of the saved system image must be guaranteed. Such a system image can be expected to contain information from many data sets (e.g., network configuration information) and information relating to the location of many data sets.

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Integrity of System Images for a Save/Restore IPL Function in an Operating System

To improve the time it takes to establish a particular system to the point where productive program execution can take place on initial program loads (IPL) other than the first, the first IPL is allowed to proceed to a point where the initialization of most of the time-consuming components is completed and the system image (contents of registers, storage, etc.) at that point is saved. A subsequent IPL using such a system image as a starting point established by restoring that image can be completed very quickly, but the integrity of the saved system image must be guaranteed. Such a system image can be expected to contain information from many data sets (e.g., network configuration information) and information relating to the location of many data sets. If a data set, that contributed information to a particular system image, is modified, that image will contain incorrect information. Similarly, after a data set whose location is recorded in a particular saved system image is moved or deleted, that image will again contain incorrect information. Accordingly, each saved system image is marked valid/invalid and each related system element, subsequent processing of which will destroy the integrity of that image rendering that element selectively sensitive, is marked sensitive to that image at the time the image is saved. When a system element which is marked as being sensitive is processed, any related saved system is marked invalid if not already so marked. Generally, that information, the change of which will invalidate a saved system image, resides in data sets or relates to data sets (such as a disk pointer to a data set). Integrity of system images requires the tracking of modification of data sets and their attributes, and involves subtasks. The first subtask is to identify dynamically the sensitive data sets. Thus, if a data set is connected to, up to the time of saving of a system image, its profile is marked sensitive. The second subtask is that of tracking changes such as those caused by modifying, moving or deleting the IPL sensitive data sets. To track data set changes, every WRITE or COPY or DELETE operation to a data set checks w...