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How are extents used in determination of dataset allocation?

 
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anirthak

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PostPosted: Tue Sep 15, 2009 12:41 pm    Post subject: How are extents used in determination of dataset allocation?
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Hi!

I have the following piece of dataset information as attchment. I'd request anyone to help me in calculation of the total tracks used.

Also I knew that the max no of extents possible is 16 (1-primary+ 15-secondary). But I found that 31 extents have been allocated for this dataset. Could someone explain this concept?

Regards,
Anirban
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Robert Sample

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PostPosted: Tue Sep 15, 2009 3:38 pm    Post subject:
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Quote:
Also I knew that the max no of extents possible is 16 (1-primary+ 15-secondary)
1. This applies to a pack -- not to a data set.
2. The system will allocate the primary space in up to 5 extents, not 1.
3. The number of secondary extents possible is 16 minus the number of extents used to allocate the primary, not 15.
4. These numbers do not apply to VSAM files or PDSE files or HFS / zFS file systems
5. Your data set is on multiple packs so the theoretical number of extents is 16 times the number of packs
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gcicchet

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PostPosted: Tue Sep 15, 2009 3:43 pm    Post subject:
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Hi,

the dataset is spanning across more than 1 volume, you are allowed 16 extents per volume.

If you hit enter again, you will see all the used volumes.

Used tracks is the total number of tracks used across all volumes.

Gerry
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gcicchet

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PostPosted: Tue Sep 15, 2009 3:45 pm    Post subject:
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Robert,

I will need to type quicker or just check if you are online icon_lol.gif


Gerry
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Robert Sample

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PostPosted: Tue Sep 15, 2009 3:54 pm    Post subject:
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LOL Gerry -- sometimes I'm faster, sometimes you are!
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gcicchet

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PostPosted: Tue Sep 15, 2009 4:00 pm    Post subject:
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Robert,

I'll steal one of your lines
Quote:
That's not what my wife tells me .....


Gerry
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Robert Sample

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PostPosted: Tue Sep 15, 2009 4:02 pm    Post subject:
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Hey! That resembles me! icon_smile.gif
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anirthak

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PostPosted: Tue Sep 15, 2009 4:10 pm    Post subject: Reply to: How are extents used in determination of dataset a
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Thanks Robert for the clarification.

In this case, what are the total no tracks allocated for this dataset? An early reply is eagerly anticipated from all the expert minds of this forum.

Regards,
Anirban.
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Robert Sample

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PostPosted: Tue Sep 15, 2009 4:28 pm    Post subject:
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It says 145,266 -- why would you not believe it?

Cross check by hitting enter on that screen and then look at how many tracks are allocated on each pack and adding the numbers together.
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anirthak

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PostPosted: Tue Sep 15, 2009 4:35 pm    Post subject: Reply to: How are extents used in determination of dataset a
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I understand Robert.
Only thing is, when I pressed 'enter' to view the multiple packs, it shows up the pack names only...not the number of tracks on each pack...i guess it might depend on the mainframe shop of my orgranization.

anyways...thanks for the information and help.

Regards,
Anirban
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Robert Sample

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PostPosted: Tue Sep 15, 2009 4:38 pm    Post subject:
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You write down the pack names on the screen.

You go to ISPF 3.4, erase the file name, put in the first pack name in the Volume Serial field and hit enter. Find the data set, record the number of tracks used on that pack, hit PF3, and repeat until you've done every pack the data set is on. Add the values you recorded up and you will have the total used by the data set.

You have to do a little work, but it doesn't really depend upon your site -- this is standard TSO/ISPF.
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