Delta Save merge block counts vs PLOG copy DSIM block counts

We are running ADA851, ADE851 and AZP851 on a z/OS 2.1 IBM environment.

I just noticed this, but I have not had any issues on the occasions where I have ever restored from Delta Save-driven weekly’s and delta merges.

When the PLOG flips after performing an online Delta Save operation, the PLOG copy includes statistics of the Delta Save image (DSIM) blocks encountered between the SYN1 and SYN2 checkpoints as the example below:



DSF031 SYN1 Checkpoint encountered on Protection Log
PLOGNUM = 207 BLOCKNUM = 2420333

DSF032 SYN2 Checkpoint encountered on Protection Log
PLOGNUM = 207 BLOCKNUM = 2420388

DSF039 DSIM Dataset completed

   DSIM Dataset Statistics:                       
       0% Full                                    
     123  ASSO Block Images Written               
      51  DATA Block Images Written               
       0  New AC Blocks Recorded                  

Then when the Delta merge is performed later, when including the DSIM data in the merge process, it includes stats about that:



DSF045 Input OFFLINE DELTA Save tape opened
DSID = 1 / 1171 - 1173 / 2022-04-19 23:01:27

DSF045 Input ONLINE DELTA Save tape opened
DSID = 1 / 1174 - 1174 / 2022-04-20 23:01:28

DSF049 DSIM Dataset statistics:

     107  ASSO Blocks present                    
      35  DATA Blocks present                    

DSF047 Output OFFLINE DELTA Save tape completed
DSID = 1 / 1171 - 1174 / 2022-04-20 23:01:28

I find it odd that the DSIM ASSO & DATA block counts from the PLOG copy process do not match the block counts from the Delta merge process.

Should I be concerned about the integrity of the delta merges and by inference the full offline DB save equivalent since for so long it has been driven by Delta Saves, daily merges and weekly merges (as is evidenced by the fact my DSID is 1 / 1171-1174)?


Brian Johnson

An likely explanation could be that the same RABN’s are written repeatedly to DSIM - that EG. DS block 4711 is written and then overwritten a number of times on the DSIM. Check that the “blocks present” are always less than or equal to “Images written”.

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