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How to increase the performance of the VSAM file

 
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maheshurstd

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Joined: 16 Feb 2006
Posts: 14

PostPosted: Mon Jun 26, 2006 12:37 pm    Post subject: How to increase the performance of the VSAM file
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Hi,

I am regularly doing the read, write, update, delete on a VSAM file, after some time the performance becomes down & i want to increase the performance of VSAM file after it has been defined.

would it be possible to increase the performance, If any one has the solution please send it

Thanks in advance

Regards

Mahesh
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Marso

REXX Moderator


Joined: 13 Mar 2006
Posts: 1232
Location: Israel

PostPosted: Mon Jun 26, 2006 5:15 pm    Post subject:
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There is not one rule to improve performance on a VSAM file: it depends very much on how records are read and how they are written.
For example, here are a few points:
  • If the inserts are done at the end of the file, then FREESPACE is not very useful.
  • If inserts are done all along the file, giving some freespace will help.
  • Use LISTCAT to check if there are CI splits. If yes, it may be necessary to increase the freespace or reorganize the file.
  • Random reads are faster when the CISZ is small. For sequential reads use a large CISZ.
  • Check also the BUFSP parameter. Try combinations like small CISZ/large BUFSP or large CISZ/large BUFSP, and so on, until you get a good performance.
Each case is different, so you will certainly have to try different options and see which one is better for you.
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die7nadal

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Joined: 23 Mar 2005
Posts: 156

PostPosted: Tue Jun 27, 2006 6:16 am    Post subject:
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Try Googling out VSAM performance docs also get the doc 'Vsam Dymystified' from IBM redbook. There are lots of good articles.
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