Gadi
When we migrated from z/OS 1.9 to 1.11 we were hit by APAR OA33307 which
caused excess paging.
Description
-
At z/OS R11, if system is >2Gig REAL, RSM will schedule an SRB
( IAXUO IARUOGBS ) to perform Frame Steal operations running
under the *MASTER* asid if a PageFix against HighVirual (64bit)
storage is done and no High Frames ( > 2Gig Real) are available.
RSM attempts to protect 31bit Real Frames as best as possible
by first stealing 64bit real frames if none are available. This
causes whichever jobs that originally owned those frames (often
DB2) to be paged out to AUX when at R10 this was either done to
a much smaller extent or not at all. Whichever job/application
owns the most High Frames ( >64bit) is most likely to experience
the highest number of frames being stolen and thus an increase
in AUX Slots. This can *potentially* (though not always)
result in performance delays for that application when those
pages have to be paged back in to real frames.
This problem is usually seen almost immediately upon migrating
to z/OS R11, and especially if Real storage is between
2Gig - 4Gig OR (for systems > 4Gig) all of the High Frames
( >64Gig ) are in use. For systems between 2Gig - 4Gig the more
predominant external symptom is abnormally high CPU in *MASTER*,
running under IARUOGBS ( IAXUO ).
ADDITIONAL SYMPTOMS:
MsgIAR005E may be issued if reconfigurable storage is present.
You might want to check that you have the PTF for this APAR applied
HTH
Mike
On Thu, May 5, 2011 at 5:16 PM, Chip Grantham <[email protected]>wrote:
> There's a CPU hit ptf for *master* doing work on available frames queue.
> It might show up as a paging issue on your system. Might want to check it
> out.
>
> Chip Grantham | Ameritas | Sr. IT Consultant | [email protected]
> 5900 O Street, Lincoln NE 68510 | p: 402-467-7382 | c: 402-429-3579 | f:
> 402-325-4030
>
>
>
>
>
> Lizette Koehler <[email protected]>
> Sent by: IBM Mainframe Discussion List <[email protected]>
> 05/05/2011 08:19 AM
> Please respond to
> IBM Mainframe Discussion List <[email protected]>
>
>
> To
> [email protected]
> cc
>
> Subject
> Re: Paging increase when going from z/OS 1.9 to 1.11
>
>
>
>
>
>
> >Hi,
> >
> >We are seeing a paging increase after upgrading to z/OS 1.11.
> >
> >Has anyone else seen this?
> >
> >TIA
> >
> >Gadi
>
>
>
> When we went from 1.9 to 1.11 we saw this effect. We were directed to a
> GRS PTF. I would open an ETR with IBM to see what other things they might
> have on this issue.
>
> This has helped to reduce our paging.
>
> Lizette
>
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