Determine tracks and cylinders



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Determine tracks and cylinders

Postby satishmf » Mon Jun 08, 2009 12:15 pm

While creating a dataset PDS or PS how do we determine the number of tracks or cylinders to allocate?
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Re: Determine tracks and cylinders

 

Re: Determine tracks and cylinders

Postby satishmf » Mon Jun 08, 2009 12:43 pm

Forgot to include how to find Block size?
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Re: Determine tracks and cylinders

Postby expat » Mon Jun 08, 2009 4:09 pm

Number of records = 100000, RECFM=FB, LRECL=125

Blocksize = INTEGER(27998 / LRECL) - Although specifying only RECFM and LRECL will invoke system determined blocksize.

Records per block = Blocksize / LRECL
Records per track = Records per block * 2
Records per cylinder = Records per track * 15

For VB records it is safest to use the maximum LRECL to determine the space requirements, but always use 27998 as blocksize.
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Re: Determine tracks and cylinders

Postby Bill Dennis » Mon Jun 08, 2009 7:50 pm

The BLKSIZE suggested by expat (27998) is one-half of a 3390 track, the most common device geometry. Smaller blocks waste space due to the physical method of writing the data on the disk.

This link shows the various block sizes and utilizations. http://publibz.boulder.ibm.com/cgi-bin/ ... 1001/B.1.2
Regards,

Bill Dennis

Disclaimer: My comments on this forum are my own and do not represent the opinions or suggestions of any other person or business entity.
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