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Formula for calculating CI size for VSam dataset

 
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ilan

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Joined: 24 Feb 2006
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PostPosted: Fri Feb 24, 2006 11:38 am    Post subject: Formula for calculating CI size for VSam dataset
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hi,

Please let me know if you have the formula for calculating the Control interval size ( both data CI & Index CI) for VSAM data set. the information i have is the lecord length is 150bytes (fixed). Please eloborate more about the variables used in the formula. as soon as possilbe.
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spiderman

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PostPosted: Fri Feb 24, 2006 12:28 pm    Post subject: Re: Formula for calculating CI size for VSam dataset
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ilan wrote:
hi,

Please let me know if you have the formula for calculating the Control interval size ( both data CI & Index CI) for VSAM data set. the information i have is the lecord length is 150bytes (fixed). Please eloborate more about the variables used in the formula. as soon as possilbe.


HI,
I dont think there is any formuale for calculating the CI size. As per my knowledge, the control interval can range from 512 to 32,768 bytes in size. If the size is between 512 and 8,192 bytes, a multiple of 512 should be specified. If it is between 8,192 and 32,768 bytes, a multiple of 2,048 should be specified. If the size is not a multiple of the appropriate value, VSAM rounds the size up to the next appropriate multiple. If CONTROLINTERVALSIZE is specified for the INDEX component of a KSDS, the specified size must be 512, 1,024, 2,048, or 4,096.

Regards
Spider
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ilan

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PostPosted: Fri Feb 24, 2006 1:40 pm    Post subject: Re: Formula for calculating CI size for VSam dataset
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hi

thank you for your immediate response. even i know the same thing. but it is stated that " size of the control interval depends on the maximum size of the data records and the amount of buffer space you provide" in a material. if this is true there must be a formulae / way to calculate the CI size with the help of record lenght, RDF size, CIDF size and the freespace percentage.

Also if we can get the number of records in a CI we can calculate the CI size. if you have any idea how to get the number of records in a CI, please let me know.
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spiderman

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PostPosted: Fri Feb 24, 2006 2:09 pm    Post subject:
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Hi,

For fixed record length files, the RDF will give the number of records in a CI. There will be 2 RDFs for fixed length records in one CI. One RDF will contain the number of records and other will contain the record length. CIDF will contain the amount of freespace. RDF will be of 3 bytes and CIDF will be 4bytes. Inside the RDF i donno how to check the number of records. I think whatever i written above, you also know. Only this much i am aware of.

Regrds
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satya123
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PostPosted: Fri Aug 25, 2006 12:15 pm    Post subject:
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hi,
please tell me if 2 RDFs are present then how you say RDF will have 3 bytes?????It must be 6 bytes of RDF and 4 bytes of CIDF..Please clarify...

satya123
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ofer71

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PostPosted: Fri Aug 25, 2006 1:43 pm    Post subject:
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Aalthough there is no single formula, the fine manual provides some guidelines. Some sites use their own CI calculators. I've seen one written in REXX and another one in CLIST.

O.
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satya123
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PostPosted: Fri Aug 25, 2006 3:36 pm    Post subject:
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My question is whether we have 2 RDFs or One????If two then total how many bytes of RDF presents in one CI?????
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