Portal | Manuals | References | Downloads | Info | Programs | JCLs | Mainframe wiki | Quick Ref
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Profile Log in to check your private messages Log in
 
Optimum Declaration for VSAM performance...!

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> JCL & VSAM
View previous topic :: :: View next topic  
Author Message
jones.jebaraj84

New User


Joined: 26 Nov 2008
Posts: 10
Location: India

PostPosted: Fri Mar 20, 2009 12:14 am    Post subject: Optimum Declaration for VSAM performance...!
Reply with quote

Hi All,

I have a KSDS VSAM file with 16 digit key and record length 17500. when i am seaching for records in this file, the job runs more than 30 mins thus giving poor performance. I tried the Buffering parameters BUFND and BUFNI and was able to reduce the job run time to 13 mins. Is there any way i can still reduce the run time.

Which could be the optimum CI SIZE and other parameters i can use to get the optimum performance...

Thanks... icon_smile.gif
Back to top
View user's profile Send private message

dick scherrer

Site Director


Joined: 23 Nov 2006
Posts: 19270
Location: Inside the Matrix

PostPosted: Fri Mar 20, 2009 12:28 am    Post subject:
Reply with quote

Hello,

Quote:
when i am seaching for records in this file,
How many "hit" records are you searching for? If you are searching for a few records by key, the process should run in a few seconds.

How many records are in the file? Is it possible that your "search" must pass all of the records rather than accessing records directly?
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8165
Location: East Dubuque, Illinois, USA

PostPosted: Fri Mar 20, 2009 1:14 am    Post subject:
Reply with quote

Post a LISTCAT for the file. Are you searching with a program or utility?
Back to top
View user's profile Send private message
jones.jebaraj84

New User


Joined: 26 Nov 2008
Posts: 10
Location: India

PostPosted: Fri Mar 20, 2009 8:58 pm    Post subject:
Reply with quote

My File has about 100 records with unique keys (16 digits). I have a main File which has about 10 million records. Each record in the Main file will have one match in my VSAM file (100 reocrds).
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8165
Location: East Dubuque, Illinois, USA

PostPosted: Fri Mar 20, 2009 9:05 pm    Post subject:
Reply with quote

Your original post talks about slow search times for a VSAM file. Now you're talking about two VSAM files. Are you even sure you know what you're attempting to do? It's not clear on this end what you're asking.

And you've been asked to provide data which I'm not seeing. When you are searching, how are you searching -- language (or utility), access method, and other such information would be helpful (as in critical, as in don't give us something to understand your processing you're not likely to get any help).
Back to top
View user's profile Send private message
jones.jebaraj84

New User


Joined: 26 Nov 2008
Posts: 10
Location: India

PostPosted: Sat Mar 21, 2009 2:56 am    Post subject:
Reply with quote

Apoligize if i am not clear on my question.

Plesae find the details as below:

Main File (Non VSAM Flat file) - 10 million records (approx)
VSAM file - 100 records approx
Language : COBOL, JCL

My program takes one record from the Main file and froms a 16 digit key. This 16 digit key from the main file is matched with the VSAM key to find for a exact match. If the match is found that particular VSAM record is processed and output is written to a flat file.

I am in the process of improving performance of this program. Now the job runs 15 mins. And this is because for every instance in the main file a VSAM search is done in the VSAM file. there are many I/O operations taking place in this process. Is there any way i could minimise the time the job runs.
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8165
Location: East Dubuque, Illinois, USA

PostPosted: Sat Mar 21, 2009 3:24 am    Post subject:
Reply with quote

Load the VSAM records into a COBOL table. Use SEARCH ALL on the table. That cuts the VSAM file reads to a minimum -- once per record to load the table.
Back to top
View user's profile Send private message
dick scherrer

Site Director


Joined: 23 Nov 2006
Posts: 19270
Location: Inside the Matrix

PostPosted: Sat Mar 21, 2009 3:33 am    Post subject:
Reply with quote

Hello,

And when loading the vsam data into the cobol table/array, make sure the table is loaded in key sequence. . .
Back to top
View user's profile Send private message
jones.jebaraj84

New User


Joined: 26 Nov 2008
Posts: 10
Location: India

PostPosted: Mon Mar 23, 2009 10:50 pm    Post subject:
Reply with quote

Thanks a lot... icon_smile.gif
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> JCL & VSAM All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
No new posts VSAM RLS Wait time blayek JCL & VSAM 2 Mon Oct 02, 2017 9:05 pm
No new posts Multiple VSAM files single output fil... Mohan Kothakota DFSORT/ICETOOL 11 Wed Aug 09, 2017 7:57 pm
No new posts CONTIG for performance? JPVRoff JCL & VSAM 8 Fri Jun 09, 2017 8:39 am
No new posts VSAM Space Allocation mrgnndhmk JCL & VSAM 7 Sat Apr 22, 2017 12:42 am
No new posts Updating a VSAM file with DISP=OLD sheersh JCL & VSAM 8 Tue Mar 14, 2017 6:14 pm

Facebook
Back to Top
 
Job Vacancies | Forum Rules | Bookmarks | Subscriptions | FAQ | Polls | Contact Us