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SIze of Tape DSN


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rahulbank

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Joined: 25 Sep 2008
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PostPosted: Sat Apr 25, 2009 12:33 am
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Hi,

Is there a way to find out the size of a Dsn in terms of either tracks or bytes which resides on a TAPE(and this is not an HSM tape).
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Robert Sample

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PostPosted: Sat Apr 25, 2009 12:53 am
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If you know the number of blocks on the tape and the block size, you can compute it easily enough. What information do you have about the tape?
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rahulbank

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PostPosted: Sat Apr 25, 2009 1:12 am
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I know the number of blocks the dsn has on the tape by viewing the job log in sar and the block size too of the tape....
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Robert Sample

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PostPosted: Sat Apr 25, 2009 1:19 am
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Multiply block size times number of blocks to get bytes in file. Use the usual formula to convert bytes into tracks or cylinders. And be aware the counts may be a little different if the file is variable instead of fixed length records.
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Terry Heinze

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PostPosted: Sat Apr 25, 2009 6:23 am
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...and even for an FB file, the last block may not be a full block.
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rahulbank

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PostPosted: Tue Apr 28, 2009 7:03 pm
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Thanks for the answer I had this question in my mind for along time...Two more things...

Do you know how to convert the tracks to blocks.
Also in case the file is variable is there a way to calculate the same tape DSN.
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Robert Sample

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PostPosted: Tue Apr 28, 2009 7:15 pm
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I'm not 100% sure I understand what you mean by "convert the tracks to blocks". Your original question was about a tape -- which has no tracks to convert. A 3390 track is blocked typically around half track blocking which is 27998 bytes, although any block size can be used.

A variable length file is much harder to calculate. For example, if the program writing the records is COBOL, the AWO compiler option affects the file. If you have SYNCSORT installed at your site, the HISTOGRM variable record analyzer will give you the numbers to make your calculation. There may be an equivalent DFSORT utility but I've never looked for one so you'd have to ask on the DFSORT forum.
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