IMSDB - DBRC
Download as PPTX, PDF3 likes1,618 views
DBRC (Database Recovery Control) is an IMS tool that controls logging and recovery of IMS databases. It stores database recovery information in RECON (Recovery Control) data sets. DBRC manages log control, recovery control, and share control through these records. It controls online log data sets, secondary log data sets, and other logs to enable full or time stamp recovery of databases. DBRC also controls database sharing levels to determine which subsystems can access and update databases.
IMSDB - DBRC
- 2. It is a part of IMS DB.We can recover and maintenance databases with it The main functions are Log control Recovery control Share control
- 3.
- 4. IMS communication with DBRC is performed through the use of threeVSAM KSDS data sets, called Recovery Control (RECON) data sets. The RECON data sets contain all of the recovery information used in recovering registered databases. RECON data sets contain several types of records, each of which is associated with a particular function of DBRC A RECON header record is created for each RECON data set to provide information that DBRC uses in managing the system. Other records are created to maintain log control, change accumulation, image copy, database data set, reorganization, and recovery information.
- 5. DBRC controls the use and availability of OLDS(online log datasets), SLDS, RLDS, and interim log data sets. Information about the logs is stored in a set of RECON data set records called log data set records. If you requested dual logging, they are referred to as PRILOG (the primary log) and SECLOG, (the secondary log). DBRC also creates log allocation (LOGALL) records to identify a database that was changed while its log data set was open.
- 6. DBRC controls the recovery of databases by supplying the necessary input for the IMS Recovery utility. To use the recovery control portion of DBRC, you must register your databases with DBRC. Recovery control does not choose the correct utility to be run at the correct time. For example, you must select the correct utility to run in the following circumstances: ▪ image copy after reorganization ▪ recovery after database I/O error ▪ backout after batch failure ▪ /ERE after online failure
- 7. A full recovery means that you have restored all of the database updates that were performed since the image copy was taken. It requires a valid image copy of the database, all log data sets created since the image copy was taken, and any change accumulation data sets. A full recovery is most often used when the data has not been corrupted but the database has been lost through something like a hardware or reorganization failure.The data was not corrupted; the database simply crashed.
- 8. A time stamp recovery recovers the database to a selected point in time. A time stamp recovery can use any image copy of the database.Then updates (using logs and change accumulation data sets) are applied up to a selected point in time. A time stamp recovery is usually used when the database has been corrupted through a processing error such as faulty application logic.
- 9. This can be achieved by registering database with dbrc, and to define share level SHARELEVL 0 No sharing. The database can be accessed only by the subsystem to which it has been authorized. SHARELEVL 1 Database-level sharing. The owner subsystem can perform updates, but other subsystems are read only. SHARELEVL 2 Intra-host block-level sharing. Subsystems executing on the same MVS have full update authority. SHARELEVL 3 Inter-host block-level sharing. Subsystems operating on the same (or any other) MVS have full update authority.
- 10. Read more at: ftp://service.boulder.ibm.com/eserver/zseries/au dio/pdfs/Part_12_V9_DBRC.pdf