DFSMShsm FRRECOV enhancement to control FC relationship after FC background copy completion

With the current behavior of the FRRECOV CP(nn) processing in DS8K incremental FlashCopy environment, the FC relationship is withdrawn after FC background copy (BGC) completion. Therefore full volume copy is needed on next FRBACKUP CP(nn) incremental processing. In addition, when they want to recover data from backup pool again by FRRECOV CP(nn), full volume copy is also needed. For example, FRBACKUP CP(nn) incremental command establish or resync FC from A to B volumes. In this environment, after the customer issues FRRECOV CP(nn) and updated tracks has been copied from B to A, FC relationships from B to A will be withdrawn. Therefore, next FRBACKP CP(nn) incremental processing will establish incremental FC from A to B which needs full volume copy. The customer has 100 TB for A volumes while amount of updates per day is 3 TB. It is estimated that 100 TB background copy(BGC) will take 24 hours with our proposed DS8K configuration, which may impact production's I/O performance and may limit the restore capability with FC FRR function. Therefore, we need the ability to control to keep FC relationship or not after FRRECOV CP processing. If DFSMShsm FRRECOV CP processing keeps incremental FC relationship, the customer can continue FRBACKUP CP incremental processing with only updated tracks background copy. So, the customer doesn't need to pay attention for their production's I/O performance generally after FRRECOV processing due to short time FC BGC.

Actually, the customer wants to have two incremental FC, say, A->B and A->C. They will take FC A->B before their batch window and take FC A->C after their batch window. In addition, on the weekend, they will take incremental FC A->B/C again and then will do their application test on A (Production volumes). After testing completion, they will restore FC B->A then starts their production. On next day, they will take FC A->B before batch window, which will cause full volume copy for 24 hours. This long time BGC is not acceptable by the customer. They are doing similar volume backup processing by Hitachi disk's copy solution (Shadow Image) without Db2 relationship. The customer wants to do similar way with Db2 relationship by using our Db2 SLB solution. However, the current FRRECOV CP behavior (withdrawing FC relationsips) cause much concern to the customer. Therefore, we need this enhancement with Db2 side support if necessary.

We believe bellow hsm procedure is needed at least.

1. FRRECOV CP(cpname) has a parameter to control if FC relationship will be withdrawn or not after FC BGC.
2. Through the output from the LIST CP(cpname) command, customer can recognized the reversed FC relationship status.
3. Through the FRBACKUP CP(cpname) withdraw commands, customer can withdraw B->A relationship while keeping backup on C. The current hsm code may do this.
4. Through the FRBACKP CP(cpname) incremental commands, customer can reverse FC relationship from B->A to A->B.