what is the minmum size of a dataset?



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what is the minmum size of a dataset?

Postby deppquestcage » Tue Nov 23, 2010 7:54 pm

what is the minmum size of a dataset?
should it be FB or VB?
Is there any other specification to be taken into account before creating a dataset with minimum size?
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Re: what is the minmum size of a dataset?

 

Re: what is the minmum size of a dataset?

Postby Akatsukami » Tue Nov 23, 2010 8:19 pm

Do you mean "What is the smallest amount of DASD or tape that can be allocated to a data set" or "What is the shortest LRECL that a data set can have"?
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Re: what is the minmum size of a dataset?

Postby steve-myers » Wed Nov 24, 2010 2:23 am

Akatsukami has it right. Do you mean amount of space, or do you mean a minimum length logical record?

You can allocate a data set with no tracks. Obviously you cannot store any data in such a data set, but you can allocate it.

The FB or VB issue depends on what you plan to put into the data set. Many programmers are uncomfortable using data sets with varying length records, but I've been doing this for close to 40 years so it's second nature to me.

One not so obvious issue might be what is the minimum block size? I would advise 18 bytes, which might also be advisable for a minimum logical record length. The reason for this is on magnetic tapes a record that is less than 18 bytes, and if it is read in error, the record would considered noise and simply discarded without attempting to reread the record or notifying your program. I don't know if this is still true with modern tape drives, but it was certainly true many years ago.
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Re: what is the minmum size of a dataset?

Postby deppquestcage » Wed Nov 24, 2010 9:46 am

Thanks for your reply....
I meant minimum amount of space(dasd) that can be allocated to a single dataset?
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Re: what is the minmum size of a dataset?

Postby steve-myers » Wed Nov 24, 2010 10:12 am

deppquestcage wrote:Thanks for your reply....
I meant minimum amount of space(dasd) that can be allocated to a single dataset?
That's what I thought you meant yesterday. One track for a data set on older DASD, in the "track managed" space on volumed with "extended attributes," or 21 cylinders in the cylinder managed space of "extended attribute" volumes.
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Re: what is the minmum size of a dataset?

Postby deppquestcage » Wed Nov 24, 2010 1:07 pm

Thank you very much for the information
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