Tape drive contention

In a tape environment where contention for tape drives may be a consideration, Table 1 shows BACKUP(bfreq) or MIGRATION(mfreq) values recommended when recycling single-file-format cartridges. BACKUP(bfreq) and MIGRATION(mfreq) are subparameters of the SETSYS RECYCLEINPUTDEALLOCFREQUENCY command.

Table 1. Recommended RECYCLEINPUTDEALLOCFREQUENCY Values
Type of Environment	Value	Resulting Allocation
A single IBM® 3494/3495 Tape Library Dataserver environment having all compatible drives	0	The input unit is allocated for the duration of recycle processing.
An SMS-managed tape environment that has multiple IBM 3494/3495 machines where inputs can come from different ATLs	0	A unique allocation is allowed for each input connected set.
A BTLS-managed environment that has multiple IBM 3494/3495 machines where inputs can come from different ATLs	1	RECYCLE allocates tape drives for each connected set in the correct library.
A multiple non-SMS-managed tape library where not all backup or migration tapes are in a single library (for example, an STK ACS cluster where you want to prevent pass-through processing)	1	RECYCLE allocates tape drives for each connected set in the correct library.
An environment that has incompatible tapes even though they may appear the same, including when one has a mix of real and emulated devices, such as 3490s and emulators of 3490s	1	RECYCLE allocates tape drives for each connected set.
A tape environment with manual tape operators, but no incompatible mix of real and emulated devices appearing as the same device	5 or 10	New allocations are allowed every 5 to 10 input connected sets.

Note: Input units are always deallocated between connected sets when the tape volumes are not single file format cartridges.