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Understanding DFSORT dynamic allocation better.

 
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vasanthz

Global Moderator


Joined: 28 Aug 2007
Posts: 1532
Location: Chennai

PostPosted: Thu Sep 20, 2007 1:00 pm    Post subject: Understanding DFSORT dynamic allocation better.
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Hi,

Wonder if you could help me with this. icon_rolleyes.gif

A large dataset say 10,000 Cyls needs to be sorted.
with the option,
OPTIONS='DYNALLOC,SORTWKNO=1',SORT=100,


As you can see, the SORTWKNO is very less,
Is there any rule to choose the optimal SORTWKNO specification
and the BUFNO specification.

Also could you please let me know the effect, if large SORTWKNO is mentioned, say SORTWKNO=10 , and BUFNO=60.


Thanks in advance. icon_biggrin.gif
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murmohk1

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Joined: 29 Jun 2006
Posts: 1439
Location: Bangalore,India

PostPosted: Thu Sep 20, 2007 1:09 pm    Post subject:
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Vasanth,

Your Sep 18 2007 post -

http://www.ibmmainframes.com/viewtopic.php?t=24563&sid=e87c2d6feef910a54fff2f88403d7ef7

I belive Frank had replied this.
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vasanthz

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Joined: 28 Aug 2007
Posts: 1532
Location: Chennai

PostPosted: Thu Sep 20, 2007 1:14 pm    Post subject:
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Hi murmohk,

I wanted to know if there is any rule for the same.
In a generalised scenario.
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Frank Yaeger

DFSORT Moderator


Joined: 15 Feb 2005
Posts: 7130
Location: San Jose, CA

PostPosted: Thu Sep 20, 2007 9:06 pm    Post subject:
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Quote:
OPTIONS='DYNALLOC,SORTWKNO=1',SORT=100,


These seem to be options for a program that's calling DFSORT. It's not clear if SORTWKNO=1 causes one JCL SORTWKdd data set to be used or sets DYNALLOC=(,1) or does something else.

Quote:
Is there any rule to choose the optimal ... BUFNO specification.


DFSORT does not pay any attention to BUFNO for work data sets. It does it's own buffer optimization.

Quote:
Is there any rule to choose the optimal SORTWKNO specification


As I said before, the best approach is to let DFSORT allocate the work data sets dynamically. DFSORT's shipped default for the number of dynamically allocated work data sets is 4. The site can change that default. I would suggest using the site default unless there's some reason to override it.
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vasanthz

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Joined: 28 Aug 2007
Posts: 1532
Location: Chennai

PostPosted: Fri Sep 21, 2007 1:26 pm    Post subject:
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Thanks for the responce Frank. icon_biggrin.gif
I was having a misconception that increasing BUFNO will increase the performance. icon_eek.gif


Also this link might be useful for further readers.
The author of this link has thanked Frank for his support. icon_wink.gif

http://66.102.9.104/search?q=cache:JGKVGeuZDEYJ:www-03.ibm.com/servers/storage/support/software/sort/mvs/tuning/pdf/srtmltun.pdf+dfsort+tuning+parameters&hl=en&ct=clnk&cd=1&gl=in
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Frank Yaeger

DFSORT Moderator


Joined: 15 Feb 2005
Posts: 7130
Location: San Jose, CA

PostPosted: Fri Sep 21, 2007 9:01 pm    Post subject:
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Yes, that paper is available on the DFSORT website:

www.ibm.com/servers/storage/support/software/sort/mvs/tuning/
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