Fast Database Recovery (FDBR) regions

In a sysplex data-sharing environment, if one IMS subsystem fails while it holds locks on data in shared databases or while waiting for work on an external subsystem, the other sharing IMS subsystems must wait for the failed subsystem to restart and release its locks. To reduce the amount of time that the sharing subsystems must wait, you can use IMS Fast Database Recovery (FDBR) regions.

FDBR regions monitor an IMS subsystem and can automatically recover database resources (shared databases and areas) if the monitored subsystem fails. In addition, in-doubt work on an attached external subsystem can be identified by calling the External Subsystem Attach Facility (ESAF) In-Doubt Notification exit routine (DFSFIDN0), which passes an informational message that you can use to automate in-doubt work handling during recovery.

An FDBR region tracks a single subsystem, so you must set up a separate FDBR region for each subsystem that you want FDBR to track.

An FDBR region does not have to run in the same z/OS® system as the IMS subsystem it tracks, but both the FDBR region and the IMS subsystem must be in the same z/OS cross-system coupling facility (XCF) group. The FDBR region also must have access to the following IMS data sets:
  • ACBLIBx
  • MODBLKSx
  • MODSTATx
  • OLDS
  • Restart data set (RDS)
  • RECONx
  • SDFSRESLx
  • WADS

FDBR is similar to XRF in that it operates in distinct phases:

Restrictions:
  • You cannot use an FDBR region with the following types of subsystems: DCCTL, Extended Recovery Facility (XRF), or DBCTL standby.
  • While using a tracking system such as FDBR, you must not use a buffer manager that is different from that of the active system.
You do not have to register a CSL with an FDBR region. If you do register a CSL with an FDBR region, it gives you the following benefits:
  • a more complete picture of the IMSplex when looking at it from the QUERY IMSPLEX command
  • a monitor program can watch the status of FDBR using the notifications that SCI sends when an IMSplex member joins and leaves the IMSplex