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samimaktar
New User
Joined: 03 Aug 2009
Posts: 25
Location: Singapore
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Hi Guys,
The below job is running in our system on daily basis. The file ABCD.XYZ.FILE.XFR.KSDS is loaded from other files (file1 to file6).
| Code: |
//STEP0050 EXEC PGM=IDCAMS
//SYSOUT DD SYSOUT=4
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
DELETE ABCD.XYZ.FILE.XFR.KSDS PURGE CLUSTER
IF MAXCC = 8 THEN SET MAXCC = 0
DEFINE CLUSTER -
( NAME(ABCD.XYZ.FILE.XFR.KSDS) -
DATACLAS(VSAME2) -
INDEXED -
KEYS(26 0) -
RECORDSIZE(1020 1020) -
REUSE -
SHAREOPTIONS(2 3) -
SPEED -
) -
DATA ( NAME(ABCD.XYZ.FILE.XFR.KSDS.DATA) ) -
INDEX ( NAME(ABCD.XYZ.FILE.XFR.KSDS.INDEX) -
CONTROLINTERVALSIZE(4096) )
//*
//STEP0060 EXEC PGM=IDCAMS
//IN1 DD DISP=SHR,DSN=ABCD.XYZ.FILE1.KSDS
//IN2 DD DISP=SHR,DSN=ABCD.XYZ.FILE2.KSDS
//IN3 DD DISP=SHR,DSN=ABCD.XYZ.FILE3.KSDS
//IN4 DD DISP=SHR,DSN=ABCD.XYZ.FILE4.KSDS
//IN5 DD DISP=SHR,DSN=ABCD.XYZ.FILE5.KSDS
//IN6 DD DISP=SHR,DSN=ABCD.XYZ.FILE6.KSDS
//OUT1 DD DSN=ABCD.XYZ.FILE.XFR.KSDS,DISP=MOD
//SYSOUT DD SYSOUT=4
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSIN DD *
REPRO INFILE(IN1) OUTFILE(OUT1)
REPRO INFILE(IN2) OUTFILE(OUT1)
REPRO INFILE(IN3) OUTFILE(OUT1)
REPRO INFILE(IN4) OUTFILE(OUT1)
REPRO INFILE(IN5) OUTFILE(OUT1)
REPRO INFILE(IN6) OUTFILE(OUT1)
//* |
Details of file ABCD.XYZ.FILE.XFR.KSDS --> KSDS File
| Code: |
STATISTICS
REC-TOTAL---------537344 SPLITS-CI--------------2 EXCPS--------------43807
REC-DELETED------------0 SPLITS-CA------------688 EXTENTS----------------3
REC-INSERTED------516331 FREESPACE-%CI----------0 SYSTEM-TIMESTAMP:
REC-UPDATED------------0 FREESPACE-%CA----------0 X'C9FF553FB8FE3
REC-RETRIEVED-------1000 FREESPC---------20793344
ALLOCATION
SPACE-TYPE------CYLINDER HI-A-RBA-------571084800
SPACE-PRI------------276 HI-U-RBA-------571084800
SPACE-SEC------------276 |
Concern is high CA-Split as production has more than 10 times of this test data. Tried with different option, but it is also increasing the CA-Split.
With FREESPACE(04 15), CA-Splits is 828
With FREESPACE(10 20), CA-Splits is 977
Please advice what will be the FREESPACE value to reduce the CA-Splits.
Thanks in Advance.
With Regards,
Samim Aktar
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Bill O'Boyle
CICS Moderator
Joined: 14 Jan 2008
Posts: 2501
Location: Atlanta, Georgia, USA
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Try a CISZ of 18432 at the DATA level and a CISZ of 2048 at the INDEX level and go from there.
Where are your CYL allocations?
You should also download and review VSAM Demystified -
Use [URL] BBCode for External Links |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
What happens if you merge the 6 input files into a single file and then load the vsam? |
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Robert Sample
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Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA
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What is the update pattern for the data set? It appears, based on what you've posted, that new records are clustered in the file, so once a CA split occurs more records are added at that point.
Since you're using the default 4096 CI size, don't bother with CI free space -- you'd have to either change the CI size or use a free space percentage of 25% to leave enough space for a record of 1020 bytes.
What is the concern with the high CA split count? If the data set is read randomly most of the time, there would be little (if any) impact on performance. Even for sequential access, since it looks like inserts are going in the file in clusters, there wouldn't be that much impact on performance with a batch of CA splits. With what you have posted so far, my inclination would be to leave it with FSPC(0 0) and let the splits happen. If all the splits are occurring due to the load, SORT THE DATA BEFORE THE REPRO! |
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samimaktar
New User
Joined: 03 Aug 2009
Posts: 25
Location: Singapore
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My Apologies...Forgot to mention that all the below files are KSDS file
ABCD.XYZ.FILE1.KSDS
ABCD.XYZ.FILE2.KSDS
ABCD.XYZ.FILE3.KSDS
ABCD.XYZ.FILE4.KSDS
ABCD.XYZ.FILE5.KSDS
ABCD.XYZ.FILE6.KSDS
ABCD.XYZ.FILE.XFR.KSDS
@Bill: Thanks bill I will try the same.
@dick scherrer: As all the i/p files are KSDS, If I merge all of them into a single file means loading into a file. so the situation is same. Please correct me if I am wrong. |
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dbzTHEdinosauer
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Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne
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come on guys,
say again what you just said,
maybe repetition is what is necessary. |
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Robert Sample
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Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA
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| Quote: |
| so the situation is same. Please correct me if I am wrong. |
You are wrong. Unload them and sort the combined data into one data set, which is then loaded into your new VSAM file. |
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dbzTHEdinosauer
Global Moderator
Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne
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you are causing splits with your initial load of the file,
which you should not do.
in order to not have any splits
(as dick scherrer already said, and you ignored with a bad assumption)
all data loaded to the file must be in sequential order.
if you load 1 file,
then load a second,
and any of the keys of the second are within the order of the first,
you are forcing an insert which will cause a split.
sort all files into one big sequential file and then load that file.
you only have half-a-million 1000-byte records.
it is a small vsam file. |
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Bill Woodger
Moderator Emeritus
Joined: 09 Mar 2011
Posts: 7309
Location: Inside the Matrix
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You really need to understand the statistics you showed.
You have 728 cylinders allocated to your dataset. Your CA is a cylinder. That means that 688 of your 728 were used as "splits".
Look at the CI splits. Hardly anything. Meaning, as has been said, each CA is being filled after the split has occurred.
Look at your "inserts". To load a KSDS, correctly, from empty, should be zero, yet yours shows a huge proportion of the data is inserted.
Look at the increasing number of splits when you specified freespace. The freespace is unused, so more space is needed, so the number of splits increases.
If you load in Key order exclusively, you'll not get one split. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
| Quote: |
| @dick scherrer: As all the i/p files are KSDS, If I merge all of them into a single file means loading into a file. so the situation is same. Please correct me if I am wrong. |
Yup, incorrect.
When you repro the individual vsam files into sequential files you need t othen Merge them into a single file. Do not simply concatenate them as one dd statement or you will be in the same situation.
Before loading anything into the "new" vsam file, you should delete/define it. |
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expat
Global Moderator
Joined: 14 Mar 2007
Posts: 8797
Location: Welsh Wales
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| Can I ask what the worry is about actually having CA splits ? |
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dbzTHEdinosauer
Global Moderator
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Posts: 6966
Location: porcelain throne
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| expat wrote: |
| Can I ask what the worry is about actually having CA splits ? |
having them is not the problem.
not understanding why they are there, is. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
| Quote: |
| Can I ask what the worry is about actually having CA splits ? |
I seem to recall that once upon a time, there was a performance concern/issue. |
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samimaktar
New User
Joined: 03 Aug 2009
Posts: 25
Location: Singapore
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| Thanks to all of you for your valuable suggestion. I will try to merge all the ip files into a sequential file and then load into the VSAM file. |
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