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calculation for space in cylinder

 
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Baskaran
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PostPosted: Tue Jun 05, 2007 12:24 pm    Post subject: calculation for space in cylinder
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Hi,

I need 159876 bytes required for a dataset,How i can represent it in JCL space parameter in CYL

space (CYL(?,?),,)

Is there any calculation avaliable.

Thanks
Baskaran
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expat

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PostPosted: Tue Jun 05, 2007 12:43 pm    Post subject:
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Quote:
I need 159876 bytes required for a dataset,How i can represent it in JCL space parameter in CYL

How did you calculate this figure ?
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dick scherrer

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PostPosted: Tue Jun 05, 2007 6:08 pm    Post subject:
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Hello,

What kind of mainframe dataset will you define? Are you aware of different mainframe file types?

Your number sounds like a windows or unix file length.
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Baskaran
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PostPosted: Wed Jun 06, 2007 10:44 am    Post subject: Re: calculation for space in cylinder
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Hi,

This is a sequential file,this will be used as unload dataset for REORG job for a DB2 table.

We calculated this number in bytes using formulas avaialble for us from IBM utility guids.

Results of the formula suggest us,this file requires 159876 bytes,Now how to specify it in SPACE parameter.

SPACE=(cyl(?,?)

Is there any conversion formula avaliable.

Thanks
Baskaran
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expat

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PostPosted: Wed Jun 06, 2007 12:07 pm    Post subject:
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What is the LRECL & RECFM of the dataset ???

As a quick guide ..............

159876 / 27998 = 5.71026501892992 blocks of data @ 27998 (half track blocking)

5.71026501892992 = 6 blocks used

As they are half track blocks, 6 / 2 = 3 tracks used

The above assumes that all available data is used within the blocks, but in most cases this is not true - so add another 2 tracks for contingency and this totals 5 tracks. This is 0.333333333 cylinders, which gets rounded up to 1 cylinder.

So, how big was the original DB2 table ???
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Baskaran
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PostPosted: Thu Jun 07, 2007 2:36 pm    Post subject: Re: calculation for space in cylinder
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Hi ,

My total space required for unload dataset is 44059546 KB.So how i would represent it in space =(cyl(?,?) ...


Thanks
Baskaran
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expat

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PostPosted: Thu Jun 07, 2007 2:52 pm    Post subject:
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I have given you a quick method to obtain a reasonable estimate on your previous post, so all you have to do is to apply that formula to the new number of bytes quoted.
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dick scherrer

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PostPosted: Thu Jun 07, 2007 2:55 pm    Post subject:
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Hello,

Use the method Expat explained earlier.

Calculate how many blocks you need by dividing by 27998 (still using 1/2 track blocking). Round up to the next full block.

Divide the block count by 2 giving tracks (round up).

Next, an oversimplification, but divide the track count by 15 giving cyls (round up and add 10 or 15%). This would depend on how many non-database bytes were written to the unload file (if any).

That should give you enough space to hold the data.

You may want to look at the documentation for whatever you use for the unload as often that documentation provides space calculation info.
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