Supporting IMSplexes

One DBRC function that is available only in an IMSplex is that when an I/O error occurs on a RECON data set in an IMSplex and a spare data set is available, the instance of DBRC that noticed the error copies the good RECON data set to the spare, activates the spare, and deallocates the original RECON data set.

At this point in the processing, the DBRC that noticed the I/O error can automatically notify the other DBRCs in the IMSplex about the reconfiguration. Then, after the original RECON data set is deallocated, it can be deleted and redefined as the spare RECON data set.

You can access the RECON data set in either serial or parallel mode. In serial mode, the RECON data set is available only to one DBRC instance at a time because that DBRC uses a z/OS® RESERVE macro to lock the entire RECON data set while the update is in progress. In parallel mode, DBRC uses the Transactional VSAM function of DFSMS to provide record-level sharing for the RECON data set. All access to the RECON for a single DBRC request (from IMS or a command or API) is processed by Transactional VSAM as one or more transactions.

Related reading: For more information about accessing the RECON data set in parallel mode, see Accessing the RECON data sets in parallel mode.