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Maxsort in Syncsort

 
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saravananj

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Joined: 23 Nov 2007
Posts: 17
Location: Chennai

PostPosted: Thu Jul 10, 2008 5:54 pm    Post subject: Maxsort in Syncsort
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Hi All,
I tried using MAXSORT for an input of size 15GB, the maxsort job happend to consume 2 times the CPU time when compared to CPU time consumed by ordinary sort in the same LPAR.

Here are the JCLs I used for MAXSORT and ordinary syncsort,
Code:
//ALLOC EXEC PGM=IEFBR14
//BKPTDATA DD DSN=ID.BKPT.DATA,DISP=(NEW,CATLG),UNIT=WRK,
//         SPACE=(1000,(500,50))
//SORT    EXEC PGM=SYNCSORT,PARM='MAXSORT'
//SYSOUT   DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SORTWK01 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK02 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK03 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK04 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
.. and so on till....
..
//SORTWK50 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTIN  DD DSN=MYINPUT,
//           DISP=SHR
//SORTOUT DD DSN=MYOUTPUT,
//           DISP=(,CATLG,DELETE),UNIT=(WRK,30),
//           SPACE=(CYL,(800,400),RLSE),
//           DCB=(RECFM=FB,LRECL=66,BLKSIZE=27984)
//SORTBKPT DD DSN=ID.BKPT.DATA,DISP=(OLD,KEEP)
//SORTOU01 DD DSN=&&SORT1,DISP=(,DELETE),
//            SPACE=(CYL,(300,50),RLSE),UNIT=WRK
//SORTOU02 DD DSN=&&SORT2,DISP=(,DELETE),
//            SPACE=(CYL,(300,50),RLSE),UNIT=WRK
//SORTOU03 DD DSN=&&SORT3,DISP=(,DELETE),
//            SPACE=(CYL,(300,50),RLSE),UNIT=WRK
//SORTOU04 DD DSN=&&SORT4,DISP=(,DELETE),
//            SPACE=(CYL,(300,50),RLSE),UNIT=WRK
//SORTOU05 DD DSN=&&SORT5,DISP=(,DELETE),
//            SPACE=(CYL,(300,50),RLSE),UNIT=WRK
//SYSIN    DD *
SORT FIELDS=(13,4,FI,A,21,4,FI,A,25,2,FI,A)


This is the ordinary Sort JCL,

Code:

//SORT    EXEC PGM=SYNCSORT
//SYSOUT   DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SORTWK01 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK02 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK03 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTWK04 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
.. and so on till....
..
//SORTWK50 DD UNIT=SYSSQ,SPACE=(CYL,(200,200))
//SORTIN  DD DSN=MYINPUT,
//           DISP=SHR
//SORTOUT DD DSN=MYOUTPUT,
//           DISP=(,CATLG,DELETE),UNIT=(WRK,30),
//           SPACE=(CYL,(800,400),RLSE),
//           DCB=(RECFM=FB,LRECL=66,BLKSIZE=27984)
//SYSIN    DD *
SORT FIELDS=(13,4,FI,A,21,4,FI,A,25,2,FI,A)


I am also attaching the SYSOUTs of both these jobs for your reference. As per my understanding MAXSORT is supposed to have consumed lesser CPU. But in reality it is the other way round. Any reasons for not getting the desired savings?
Or did I miss something very specific to MAXSORT?
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Bill Dennis

Active Member


Joined: 17 Aug 2007
Posts: 562
Location: Iowa, USA

PostPosted: Thu Jul 10, 2008 6:31 pm    Post subject:
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By providing so many SORTWKxx files you missed the benefit of MAXSORT. It is used for sorting large files when limited sort work space is available. It will use MORE CPU but can use less sort work.

If you have a 15GB file but only 3GB of sort work space then MAXSORT will sort the file in 5 chunks and then automatically merge then to create the final SORTOUT.

We like MAXSORT because the same set of JCL can be used for a variety of file sizes and everything happens automatically.
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saravananj

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Joined: 23 Nov 2007
Posts: 17
Location: Chennai

PostPosted: Fri Jul 11, 2008 8:45 am    Post subject:
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Thanks for the explanation Bill. Infact it helped me a lot in understanding MAXSORT better.
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