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Calculating dataset size

 
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SSR
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PostPosted: Thu Jul 06, 2006 10:23 am    Post subject: Calculating dataset size
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hi,

Could anyone please let me know how to calculate the number of records a dataset can occupy based on the Primary and secondary volume and the LRECL, is there any formlae for calculating that.

And also kowing the number of records a dataset needs to hold how to allocate the primary and scondary volumes and the number of extents.

Thanks n Regards
SSR
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kondakonda

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PostPosted: Thu Jul 06, 2006 1:52 pm    Post subject: Re: Calculating dataset size
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Hi,

1 CYL = 15 TRKS
1 TRK = 56, 664 BYTES
if you define the LRECL as 56664, then one record is stored in each track.

If we define SPACE=(TRK,(3,2)), the primary allocation is 3 tracks and the secondary extents is 2 * 3 = 6 tracks.
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PostPosted: Thu Jul 06, 2006 4:44 pm    Post subject: Re: Calculating dataset size
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hi,


In the above example, what will be the number of records it can hold if the LRECL is 80 bytes.

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SSR
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kondakonda

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PostPosted: Thu Jul 06, 2006 4:56 pm    Post subject: Re: Calculating dataset size
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Hi,

In the example the data can be stored in a total of 9 tracks
for each track if the record length is 80 bytes then 708 records can be stored.
so for 9 tracks totally 6372 records can be stored.

Thanks.
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PostPosted: Thu Jul 06, 2006 5:18 pm    Post subject:
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hi,

Thank you for your information will try it out.
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PostPosted: Thu Jul 06, 2006 5:30 pm    Post subject:
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hi,

What is the Use of AVGREC parameter, what will happen if we code the AVGREC parameter ('U', 'K', 'M') along with this.

Sorry if am disturbing you..

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cpuhawg

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PostPosted: Thu Jul 06, 2006 6:22 pm    Post subject: Re: Calculating dataset size
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AVGREC is a parameter on the DD statement that allows you to basically allocate your space in records, rather than CYLs or tracks.

AVGREC can be U, K or M
U is for records requested in groups of one
K is for records request in groups of 1024
M is for records requested in groups of 1048576

Let's say you have 1,048,576 records that are 228 bytes long and you want to define the space using AVGREC

Here are the three ways:

This is for AVGREC=U in units of one
Code:

DD SPACE=(228,(1048576,100),RLSE),AVGREC=U


This is for AVGREC=K in units of 1024
Code:

DD SPACE=(228,(1024,10),RLSE),AVGREC=K


This is for AVGREC=M in units of 1048576
Code:

DD SPACE=(228,(1,1),RLSE),AVGREC=M


Allocating using AVGREC is just a different means of allocating space for a sequential file if you know how many records you are dealing with.
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kondakonda

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PostPosted: Fri Jul 07, 2006 3:14 pm    Post subject: Re: Calculating dataset size
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Hi,

Please find another example for AVGREC

// SPACE=(128,(5,2)),AVGREC=K
The space allocation indicates an average record length of 128 bytes,
a primary quantity of 5K (5,120) records,
and a secondary quantity of 2K (2,048) records.
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