Selective Logging Restore

TPFUG_Req_Number: D93005
Contact Originator Id: Jaap Termaat
Abstract: Selective Logging Restore
Description: The TPF restore package should allow for a restore of a subset of the database, (pre-)defined in a table, beyond the point at which a full system restore must be stopped due to database corruption. Thus allowing for parts of the database not affected by the corruption to be restored without losing any information.
Critical Success Factors: The implementation of this functionality will greatly reduce the ill-effects caused by a partial corruption of the database and would minimise the users' efforts to (manualy) bring the database up to date again if this is even possible.
Solution Considerations: KLM created a Selective Logging Restore Facility that allows for a restore of a subset of the database beyond the point at which a full restore must be stopped. This function is table driven and selects parts of the database to be included or excluded by the selective restore based on the record ID.
A selective restore option byte is added to the FCAP/FRST keypoint (SKBXAX, BXAXF, BXAX24, BXP)24 thru BXP724).
The "ZFRST LOG SEL" option has been added to the FCAP/FRST message parser BXPR24.
FRST Input Message Analyser BXAJ24 has been changed to call a newly created segment to check for selective restore options on the "ZFRST LOG" input message.
LOG/XCP restore restart BXBY24 has been modified to lock selective restore programs in core.
LOG/XCP restore End Of Job BXCY24 has been modified to activate a new selective restore EOJ program.
The LOG/XCP restore diskwrite program BXEY24 has been modified to let a new program do the actual disk write and if appropriate check the selective restore tables in stead of the RIAT to determine whether or not the record should be restored.
The selective restore package has five different restore options, four of which are table driven. The first two each check their own predefined table. The positive selective restore allows for restoring of all ID's defined in the third table and the negative selective restore allows for restoring all ID's except the ones defined in the fourth table. The latter two tables are assembled on demand.
The fifth and last option is the POOL option which restores all data records found on the LOG tape. All employ a "Set File Address In Use" utility to update the Son Pool Directory records 06-SDR.