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Do the IFASMFDP affect the system performance especial IO ?

 
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zos5415

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Joined: 29 Aug 2008
Posts: 18
Location: China

PostPosted: Fri Mar 21, 2014 8:23 am    Post subject: Do the IFASMFDP affect the system performance especial IO ?
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Hi Folks,

when our system encounter the responding time get longer, i always see the IFASMFDP is dumping the SMF.

Is it true ? and anyway to deduce this affection ?

Thanks !
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steve-myers

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Joined: 30 Nov 2013
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PostPosted: Fri Mar 21, 2014 2:33 pm    Post subject:
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How large are the SYS1.MANx data sets? Are you copying to disk or tape? Is the SMF data in LOG data sets or SYS1.MANx data sets.

From a practical point of view IFASMFDP does 3 things.
  • It copies SYS1.MANx data sets or SMF data in log data to sequential data sets. This is a little more complicated than meets the eye, and uses more CPU than you might think.
  • It initializes SYS1.MANx data sets, usually after they have been dumped.
  • It can copy selected data from a sequential data set containing SMF data to another sequential data set.
IFASMFDP I/O is liittle more than incidental, and should not cause any particular trouble. I've never encountered log I/O, so I can't comment as I have no experience.

I have written programs to do the first (from SYS1.MANx data, not log data) and third bullets that seem to use less CPU than IFASMFDP. I'm sure I could do the second bullet, but there is some APF stuff there to update RDS data for live SYS1.MANx data I don't know how to do, so I haven't tried it.
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Pete Wilson

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PostPosted: Thu Mar 27, 2014 2:03 pm    Post subject:
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It might be a coincidence that SMF is dumping when you look at it. It might be something else happening just before that has caused SMF to fill up and need to unload and which may be causing the initial problem.

Sheryl Watson recommends using Logstreams:
http://www.watsonwalker.com/PR120809.pdf
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