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UNIT parameter in JCL


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rinitha

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Joined: 22 Aug 2009
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Location: Chennai

PostPosted: Tue May 18, 2010 6:55 am
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I am having a JCL that has many sort steps. All the SORT steps have both input and output as TAPE files. This makes the JCL to run for 3 to 4 hours.
Is there any DASD units like TEMPDA which would make my processing time less and also hold huge data. The data size would be around 1 GB.I am not too bothered about the dataset retention duration in DASD. It is ok if retention is greater than 1 day. BAsically, i would like to know what are different types of DASD like SYSDA, TEMPDA and their differences
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dick scherrer

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Joined: 23 Nov 2006
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Location: Inside the Matrix

PostPosted: Tue May 18, 2010 7:44 am
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Hello,

You need to talk with the stoprage management people for your system.

Keep in mind that if the files are already on tape and the final output also needs to be on tape, copying them to dasd and back will probably cost more tiime. . .

If the files are to be sorted into different sequences, having them on dasd may help elapsed time, but will probably not reduce the number of i/o's and cpu required.

Quote:
i would like to know what are different types of DASD like SYSDA, TEMPDA and their differences
This is completely site-specific.
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Bill Dennis

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Joined: 17 Aug 2007
Posts: 562
Location: Iowa, USA

PostPosted: Tue May 18, 2010 8:12 pm
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You might reduce elapsed time by allocating two units for SORTIN. If the tapes require manual mounting or recall in a virtual library, using two units helps get the next volume staged prior to reading.

// UNIT=(TAPE,2), <= your device name
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