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DATACLAS=COMPRES, DASD creation in JCL

 
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paul_seth55

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Joined: 09 Mar 2009
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Location: New York

PostPosted: Tue Mar 10, 2009 2:13 am    Post subject: DATACLAS=COMPRES, DASD creation in JCL
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From what i understand, DATACLAS=COMPRES is used for DASD file to create a compressed version of file and to handle Volume issues for temporary file used in jobs. This parameter is also ignored when we provide other parameters DISP, SPACE, LRCEL, etc. This have no signigicance over TAPE files.

My question is if the Compressed DASD file is copied back to TAPE GDG version, will data be in compressed format or TAPE just consider it as a regular data and space for storage is based on the (number records+Record length+block size)?

I am working on MIPS optimization, where in 0th version Tape file is copied to DASD file with DATACLAS=COMPRES, which takes approximately 18M. The next Step creates +1st Tape version of same GDG where records from a VSAM file is copied. The final step appends the DASD created in First step into the +1 version, which only takes 3M. If i can use the 0th version in the final step, this can completly eliminate the 18M of CPU time. I just wanted to know in DATACLAS=COMPRESS have any significance.

Thanks in Advance for your reply.
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dick scherrer

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Joined: 23 Nov 2006
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PostPosted: Tue Mar 10, 2009 2:26 am    Post subject:
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Hello and welcome to the forum,

Quote:
DATACLAS=COMPRES is used for DASD file to create a compressed version of file. . .
I suspect this is something site-specific.

Suggest you speak with your storage management people for the most complete info.
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expat

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Joined: 14 Mar 2007
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PostPosted: Tue Mar 10, 2009 12:17 pm    Post subject:
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Quote:
My question is if the Compressed DASD file is copied back to TAPE GDG version, will data be in compressed format or TAPE just consider it as a regular data and space for storage is based on the (number records+Record length+block size)?

That depends on the system and hardware defined compression parameters.
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Anuj Dhawan

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Joined: 22 Apr 2006
Posts: 6258
Location: Mumbai, India

PostPosted: Tue Mar 10, 2009 2:11 pm    Post subject:
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Hi Dick,

Pardon my small experience - I believe DATACLAS are alaways site-specific.. icon_confused.gif

paul_seth55,

Quote:
I just wanted to know in DATACLAS=COMPRESS have any significance.
As an experiment, you might try with different "DATACLAS"es availabe at your end? If you have already tried, what was the result?
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paul_seth55

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PostPosted: Tue Mar 10, 2009 6:54 pm    Post subject:
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Thanks everyone for the inputs. Let me check this information with the Storage admin!
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