How to determine when REORG with LONGLOBDATA is required (DB2) REORGCHK only identifies when a reorg is required for space reclamation on normal (non-LOB) data. Is there a way of determining how many pages are wasted due to LONG and LOB data that has been logically deleted and thus indicate that a reorg with LONGLOBDATA would be beneficial?

The admin table ADMINTABINFO accurately identifies the number of pages containing LOBDATA but gives no indication of how much of that data is "real" data, and how much has been logically deleted.

eg. Before REORG with LONGLOBDATA column LOB_OBJECT_P_SIZE/32 showed 35328 pages. After the reorg it showed 2176 pages. A substantial saving. But I had no way of knowing that I would save this much until actually running the reorg.
There doesn't seem to be a specific metric that you can use, but indirectly the high ratio of FPAGES to NPAGES and, if you have indexes, INDCARD to NDEL will tell you that there is a significant number of logically deleted rows. Unfortunately, this does not work for tables where rows are UPDATEd but not DELETEd, so I guess you will just want to run regular reorgs on tables where LOB columns are regularly modified.