volcount and secondary allocation



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volcount and secondary allocation

Postby samb01 » Mon Jun 10, 2013 8:08 pm

Hello,

i would like to know the meaning of vol=(,,,15) with a System-Managed DASD Data Sets.

In the documentaation, there i :

Volume Count for System-Managed DASD Data Sets: You cannot specify a volume count for an existing system-managed DASD data set. (If you do, the system will ignore it.) When you create a new system-managed DASD data set, the volume count defined in the data class may be overridden by using the volume-count subparameter. However, if the volume-count subparameter specifies a value greater then 59, the system will set the volume count to a maximum of 59. The maximum volume count for a VSAM or System-Managed DASD data set is 59.


It is not GUARANTEED_SPACE. So i would like how will be allocated this dataset for example :

//SORTOUT   DD DSN=THGVN.JYHG.GFTR.FT,
//          DISP=(NEW,CATLG),           
//          SPACE=(CYL,(100,500),RLSE),VOL=(,,,15)         




vol=(,,,15) is for the secondary space or the primary space ?

I there no VOL=(,,,15) specified either in the JCL, either in the dataclass, what is the default ?

Thank's for your help.
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Re: volcount and secondary allocation

 

Re: volcount and secondary allocation

Postby Robert Sample » Mon Jun 10, 2013 9:09 pm

For tape data sets, the default volume count will be 5.

For disk data sets, the default volume count will be 1.

However, site SMS rules can change the defaults and therefore you really need to consult your site support group to get the information relevant TO YOUR SITE. Knowing the generic answer is not helpful if your site has changed the rules.
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Re: volcount and secondary allocation

Postby samb01 » Mon Jun 10, 2013 11:14 pm

Thank's for the answer but is it for the secondary space or the primary space ?

For example :

//SORTOUT   DD DSN=THGVN.JYHG.GFTR.FT,
//          DISP=(NEW,CATLG),           
//          SPACE=(CYL,(100,500),RLSE),VOL=(,,,15)         


the dataset can allocate 500 cylinders * 15 extent * 15 volume = 112500 cylinders ?

Is a good calcul ?
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Re: volcount and secondary allocation

Postby dick scherrer » Mon Jun 10, 2013 11:27 pm

Hello,

Do you not believe it is time you were able to look up things in the manuals :?

The following was found in less than 30 seconds in the JCL Reference manual (avauiklable via the "IBM Manuals" link at the top and bottom of the page:
Volume Count for Nonspecific Requests: If the request is for a nonspecific, public volume on a direct access device, the system ignores the volume count and allocates the number of volumes in the UNIT count subparameter.


After 3.5 years, spoon-feeding should not be required.
Hope this helps,
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Re: volcount and secondary allocation

Postby Robert Sample » Mon Jun 10, 2013 11:42 pm

Thank's for the answer but is it for the secondary space or the primary space ?
This is basically a meaningless question. Space allocations for a volume are primary followed by secondary; so asking "either - or" indicates very clearly that you have no clue about dasd space allocation and therefore you need to spend the time to read -- cover to cover -- the JCL Reference and JCL User's Guide manuals. If this takes you 3 months, then spend the 3 months to do it.

This entire topic is turning into a big waste of time.
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Re: volcount and secondary allocation

Postby BillyBoyo » Tue Jun 11, 2013 1:07 am

I'm making an educated guess that this is to do with your SORTWK question.

Whilst I'd certainly recommend efforts to improve your understanding of the various options of JCL, a great deal is down to your site's specifics and standards, especially for enormous datasets. Don't keep on struggling with it yourself. You'll find that even if you get it working yourself, it'll be changed by "Production Control" to do it the "proper" way, so get someone who will be responsible for it to do it the proper way up front, then once you see it, ensure that you thoroughly understand it.

And no, your calculation does not really work. You have to find out how the system deals with the possibility of the primary space not being available in one extent, and the same for the secondary extents.
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