OS Simulation › DMSTVS Exit › Examples of Pre-Mounting Tapes Using SLMOUNT › Increasing Performance by Increasing Input and Output File Blocksize

Increasing Performance by Increasing Input and Output File Blocksize

You can greatly increase the performance of your programs that read and write tapes if you specify a larger blocksize for the input and output files. When you use a larger blocksize, fewer I/O requests are necessary, and it is possible to write more information to each tape.

This EXEC specifies a blocksize of 4000 for the input and output files.

'VMTAPE MOUNT SCRATCH DSN LARGE.FILE ( WAIT RETPD 10'

if RC <> 0 then exit RC
'FILEDEF INMOVE DISK LARGE FILE A ( RECFM FB LRECL 80 BLKSIZE 4000'
'FILEDEF OUTMOVE TAP1 SL 1 ( RECFM FB LRECL 80 BLKSIZE 4000'

queue 'FIRST.DATA.SET'
'LABELDEF OUTMOVE FID ? VOLID SCRATCH'

'MOVEFILE INMOVE OUTMOVE'