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Difference bw NULLFILE & DUMMY

 
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subhasis_50

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Joined: 09 Mar 2005
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PostPosted: Thu May 26, 2005 9:50 am    Post subject: Difference bw NULLFILE & DUMMY
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Hi,
What is the difference between
DD DUMMY
and
DD DSN=NULLFILE
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vishal_a

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Joined: 24 May 2005
Posts: 45
Location: Noida

PostPosted: Thu May 26, 2005 11:50 am    Post subject: Re: Difference between NULLFILE & DUMMY
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icon_cool.gif hi Subhasis
well actually there is no difference b/w both
we can use sysin dd dummy or nullfile will work as same
no i/o function will be done on dataset
regards
vishal
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kanak

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Joined: 12 Mar 2005
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PostPosted: Thu May 26, 2005 12:01 pm    Post subject:
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I agree with vishal.There is no difference.
The system bypasses all input/output operations, does not
allocate devices or storage to the data set, and does not perform disposition processing.
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avalanches

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Joined: 10 May 2005
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PostPosted: Thu May 26, 2005 12:43 pm    Post subject:
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Hi,

Does it make any difference in using DUMMY or NULLFILE in the copying? Say initializing an empty file. I've used copying NULLFILE. What about DUMMY?

avalanches
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SteveConway

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Joined: 26 May 2005
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PostPosted: Thu May 26, 2005 6:45 pm    Post subject:
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The previous posters are correct, there is no difference in the processing of DD DUMMY and DD DSN=NULLFILE. There are documented restrictions on the use of NULLFILE, primarily no use as a temp file dsn or a pds name with member specified.
DSN=NULLFILE works as a nice placeholder in a proc for a file that is used intermittently, or has a varying dataset name. You can code all other attributes (DCB, UNIT, SPACE, etc.) and then just override the DSN if you need it. Of course, you can do the same with DD DUMMY; DSN=NULLFILE just lines up neater. :-)
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xstortion

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Joined: 27 May 2005
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PostPosted: Fri May 27, 2005 7:30 pm    Post subject:
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SteveConway wrote:
The previous posters are correct, there is no difference in the processing of DD DUMMY and DD DSN=NULLFILE. There are documented restrictions on the use of NULLFILE, primarily no use as a temp file dsn or a pds name with member specified.
DSN=NULLFILE works as a nice placeholder in a proc for a file that is used intermittently, or has a varying dataset name. You can code all other attributes (DCB, UNIT, SPACE, etc.) and then just override the DSN if you need it. Of course, you can do the same with DD DUMMY; DSN=NULLFILE just lines up neater. :-)


Great answer cosmetic reasons we are so vane icon_lol.gif
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enrico-sorichetti

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PostPosted: Mon Oct 17, 2016 4:33 pm    Post subject: Reply to: Difference bw NULLFILE & DUMMY
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Topic cleaned up,

posted a sticky on the same subject
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