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SYNCSORT Work Space

 
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ilakkia
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Joined: 17 May 2008
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PostPosted: Wed Jun 04, 2008 12:18 pm    Post subject: SYNCSORT Work Space
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I have two tape files each containing 8,000,000 records.
Record Length is 4000. Record format is FB.

I need to sort the two files with respect to account numbers in
position 1 to 8.
I have the sort card to be used, which will take the form
SORT FIELDS = (1,8,CH,A).

My problem is the number of sort work space datasets to use.
The sortwork datasets should use must take the below form.
SORTWK01 DD UNIT=SYSDA,SPACE=(CYL,900),DSNTYPE=LARGE

I also need the general method to find and fix the number of sortwork space if the record count is known.
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Bill Dennis

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

PostPosted: Wed Jun 04, 2008 7:08 pm    Post subject:
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I use this formula:

((Record count * 1.5) * Record size)) = total sortwork alloc in bytes

Convert bytes back to CYLS based on your DASD type.

If the total sortwk space is too large, this could also be an opportunity to use SyncSort MAXSORT which can break the total sort into smaller sort/merge phases based on your specified breakpoint sizes. Consult the product manuals.
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Guru Bob

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PostPosted: Thu Jun 05, 2008 1:24 pm    Post subject:
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Wow so easy.

Get the size of the two input files 16M records at 4000 bytes = 12 records per TRACK. I am assuming 3390 device type.

your input file size is 88,889 cylinders.

You need 124,444 CYLS of SORTWK hence need 62 SORTWKs coded at 2000 cylinders each

I also assume you have coded EXEC PGM=SORT,PARM='BMSG,ELAP,VSCORET=64MB' or added //$ORTPARM for the same parms?

to make the sort run faster - have you also coded the parameter to read both carts at once?
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gcicchet

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PostPosted: Thu Jun 05, 2008 3:50 pm    Post subject:
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Hi Guru Bob,

I'm curious to know how you read 2 carts at once.


Gerry
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Guru Bob

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PostPosted: Thu Jun 05, 2008 4:09 pm    Post subject:
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You can if using SYNCSORT

Unfortunately a HARD drive crash has lost my SYNCSORT manual so I cannot remember the exact parameter no I had to go retrieve another manual from the WEB. But it tells SYNCSORT to mount tapes on multiple volumes and read together.
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gcicchet

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PostPosted: Thu Jun 05, 2008 4:15 pm    Post subject:
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Hi Guru Bob,
maybe I'm being picky or I'm asking a dumb question, but surely it's still reading 1 record at a time.


Gerry
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Bill Dennis

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PostPosted: Thu Jun 05, 2008 6:25 pm    Post subject:
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If you code your JCL as UNIT=(TAPE,2) then two volumes will be mounted. This eliminates the delay of rewind, unload time when switching physical tapes. It's still reading one tape at a time.
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Alissa Margulies

SYNCSORT Support


Joined: 25 Jul 2007
Posts: 500
Location: USA

PostPosted: Thu Jun 05, 2008 8:23 pm    Post subject:
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Bill Dennis wrote:
It's still reading one tape at a time.
While this is true for a standard sort, PARASORT allows you to read more than one at a time. PARASORT is fully documented in Chapter 10 of the SyncSort for z/OS Programmer's Guide.

Guru Bob wrote:
Unfortunately a HARD drive crash has lost my SYNCSORT manual
Bob, contact me offline I'd be happy to help you out.
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gcicchet

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PostPosted: Fri Jun 06, 2008 3:25 am    Post subject:
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Hi Bill,

Quote:
If you code your JCL as UNIT=(TAPE,2) then two volumes will be mounted. This eliminates the delay of rewind, unload time when switching physical tapes. It's still reading one tape at a time.



There are 2 files involved and the above will only work if either file is a multi volume dataset.

Gerry
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Guru Bob

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PostPosted: Fri Jun 06, 2008 1:07 pm    Post subject:
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PARASORT is the correct parameter under SYNCSORT and is designed for multi volume cart files.
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