Re: High faulting in the System Memory Pool

[Alexei Pytel <pytel@xxxxxxxxxx>]

You can use WRKSYSACT, sort on I/O and look for tasks or jobs with lots of 
synchronous reads (database and non-database).
Another possibility - if you happen to collect performance data, look in 
QAPMJOBMI files for tasks or jobs with high synchronous reads  and/or high 
total faults.
This should give you a clue what's going on.

I would like to point out that 10 faults per second might be unusual for 
your system, but it's not excessive - with 12GB in the pool it's less than 
one fault per second per GB of storage.

    Alexei Pytel
always speaking for myself





"Graap, Ken" <keg@xxxxxxxxxxxxx>
Sent by: midrange-l-bounces@xxxxxxxxxxxx
08/06/2003 11:11 AM
Please respond to Midrange Systems Technical Discussion

 
        To:     "'Midrange'" <midrange-l@xxxxxxxxxxxx>
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        Subject:        High faulting in the System Memory Pool



I'm having an event occur on my system this morning that I'm still trying 
to
understand.

The faulting rate in the system *MACHINE memory pool skyrocketed.

I've seen this happen before when a communications recovery is in 
progress,
but I checked that out and our comm interfaces seemed to be performing 
just
fine.

I did notice that a couple batch jobs were doing big query sorts 
(QQQTSORT)
.. and when they ended the faulting rate tapered off for a few minutes. 
But
it is still at about 9.8/second with an allocation of 11GB... That is 
high.
We usually can run at 2 faults/second with about 2GB allocated. 

Does anyone have any ideas on what I might look at to determine what is
going on here?

     Pool   Reserved    Max  ----DB-----  --Non-DB---  Act- 
    Size M   Size M     Act  Fault Pages  Fault Pages  Wait 
  12368.42    672.18  +++++     .3    .3    9.4  10.9  281.0 
   2765.47      1.65    180   17.7 129.1   54.8 306.4   3855 
    655.35     12.01     15   86.9  7946   49.3 928.2    4.6 
    423.93       .00     25   92.5 729.7  159.3 492.0  586.7 
      6.96       .00      6     .0    .6    7.6  26.3   15.1 
     81.91       .00      4    1.6 106.5   13.5  27.6    9.8 
     81.91       .00      8   10.5  96.5   26.6  94.6   67.3 

thanx

Kenneth
--
********************************
Kenneth  E.  Graap
IBM Certified Specialist
AS/400 Professional
System Administrator
NW Natural - Information Services
System Services
Phone 503 226 4211 X5537
FAX   603 849 0591
keg@xxxxxxxxxxxxx
********************************

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