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mounting a multi-reel tape file

PostPosted: Thu Apr 21, 2011 4:25 pm
by Daimy Peter
Which JCL subparameter allows for mounting a multi-reel tape file onto the same physical drive?

Re: a jcl question

PostPosted: Thu Apr 21, 2011 6:05 pm
by Robert Sample
Look at UNIT=AFF

Re: mounting a multi-reel tape file

PostPosted: Thu Apr 21, 2011 9:03 pm
by steve-myers
I think Daimy Peter means to mount the tape volumes serially on one drive. This is the JCL and system default. For a multiple volume disk dataset, the system will "mount" all the volumes on multiple drives; it's been more than 30 years since removable disk drives were a common option.

Re: mounting a multi-reel tape file

PostPosted: Fri Apr 22, 2011 12:35 am
by NicC
Common description of UNIT=AFF: use the same tape unit for this DD as for that DD. For a dataset spanning multiple tape volumes the same unit is used for the next tape as for the previous. You cannot, as far as I know, mount volume 1 of 2 on one unit and volume 2 of 2 on another unit.

Re: mounting a multi-reel tape file

PostPosted: Fri Apr 22, 2011 1:08 am
by steve-myers
For input -
//INPUT    DD  DSN=dataset-name,UNIT=(tape,2),
//             VOL=SER=(vol1,vol2),DISP=OLD

If the dataset is cataloged, you can omit the VOLUME parameter, and code UNIT=(,2).

For output -
//OUTPUT   DD  DSN=dataset-name,UNIT=(tape,2),DISP=(NEW,...)

None of this is very desirable any more since most shops use virtual tape of some sort, tape library systems, or tape drive attachments to auto load tape volumes.