PERCENTVALID: Specifying the percent valid criteria for recycle eligibility

Explanation: PERCENTVALID(pct) is an optional parameter specifying the maximum percentage of valid data that a volume can have and still be eligible for recycling. DFSMShsm ignores this parameter if you specified the volume to be recycled. For pct, substitute a decimal number from 0 to 100. For example, if you specify pct as 30, a connected set (including a single volume) whose first volume in the set contains 30% or less valid data AND whose entire set contains 30% or less valid data is eligible for recycling.

Note: If 0 (zero) is specified, no tape drives are required. Only tapes that contain no valid data are returned to scratch.

By default, DFSMShsm requires the first volume in the connected set to meet the percent valid criterion before determining the connected set's percentage of valid data. To allow connected sets to be recycled earlier and potentially free up more volumes to scratch or tape pools, you can use the CHECKFIRST(N) parameter to specify that the first volume of a connected set need not meet the PERCENTVALID requirement as long as the entire connected set meets the PERCENTVALID requirement. For example:

RECYCLE PERCENTVALID(pct) CHECKFIRST(N)

Defaults: If PERCENTVALID(pct) is not specified on the RECYCLE command, DFSMShsm selects an appropriate value based on the volume type parameter specified. Also, recycle processing always performs the first volume check when evaluating the connected set's recycle eligibilty.

RECYCLE ALL is treated functionally as a RECYCLE ML2 followed by a RECYCLE BACKUP.

When processing ML2 volumes, DFSMShsm uses the ML2RECYCLEPERCENT value that has been specified on the SETSYS command. If ML2RECYCLEPERCENT has not been specified, DFSMShsm uses the SETSYS RECYCLEPERCENT value. If RECYCLEPERCENT has not been specified, the DFSMShsm default is 20%.

For all backup volume type parameter specifications (Backup, Daily, or Spill), DFSMShsm uses the RECYCLEPERCENT value.

You can override this default by specifying the RECYCLE PERCENTVALID parameter.

Note:

During RECYCLE execution, a DELVOL operation is performed for any volume having 0% valid data.
For a discussion of how DFSMShsm calculates percentages based on valid blocks and connected sets, refer to Managing DFSMShsm media.