SV: [DB2-L] Estimate EDM_SKELETON_POOL size for V9 migration?

Olle Brostrom

SV: [DB2-L] Estimate EDM_SKELETON_POOL size for V9 migration?
Gary and Phil,
We also went through the same experience.

V8:
EDMPOOL=176000,

V9 NFM when migrated and using DSNTINST calc values, bad performance in EDM_SKELETON:
EDMPOOL=176000,
EDM_SKELETON_POOL=34514,

After tuning we ended up with the following:
EDMPOOL=32000,
EDM_SKELETON_POOL=88000,

The EDMPOOL could be reduced from 176000K in V8 down to 32000K without any performance degradation.
The problem we got was to monitor the EDMPOOL because our monitor (Mainview for DB2) do not signal any performance problems when reducing the EDMPOOL. Due to the high Free Pages in EDMPOOL we beleived we could change the EDMPOOL further down, but when we did we got EDMPOOL failures!
I'm not sure about the role the EDMPOOL play in V9 NFM,
Today MV/DB2 reports the following usage:

Storage Usage.................. %Pool ÄPages
EDM / RDS Pool (Below)......... 8000
Free Pages................... 96.14 7691
Non-Stealable................ 3.86 309
CT......................... 0.85 68
PT......................... 3.01 241

Skeleton Pool (Below).......... 22000
Free......................... 0.56 123
Used for CT.................. 6.51 1432
Used for PT.................. 92.93 20445

And here is the performance today
Activity....................... Interval Session
CT: Requests.................. 7280 24636093
Loads..................... 8 20878
Hit Ratio................. 99.89 99.92
DBD: Requests.................. 44365 171.9M
Loads..................... 0 1562
Hit Ratio................. 100.00 100.00
PT: Requests.................. 252903 1.1G
Loads..................... 84 366676
Hit Ratio................. 99.97 99.97

Regards
Olle


-----Ursprungligt meddelande-----
Från: IDUG DB2-L [mailto:[login to unmask email] För McLaren Phil
Skickat: den 24 november 2009 16:09
Till: [login to unmask email]
Ämne: Re: [DB2-L] Estimate EDM_SKELETON_POOL size for V9 migration?

Gary,

I can't say I relied on the install clist, but then I had the flexibility to go high on the value for the new EDM-SKEL_POOL value and tune afterwards. I ended up with an approximate split, halving the original EDMPOOL and giving the other half to the new SKEL_POOL. If I remember correctly, much of the new pool was not consumed until we rebound. Final results we ended up with were as below (for the main production subsystem)

EDMPOOL=80000,
EDM_SKELETON_POOL=70000,

It would be interesting to know what others have found here, though of course there are a lot of variables.

I used much the same erm...'intelligence' (!) to handle the DSNDB07 rebalance for the 4K and 32K pagesets. In our case about 70% moved into the 32K pagesets from almost zero use before.

Regards
Phil


-----Original Message-----
From: IDUG DB2-L [mailto:[login to unmask email] On Behalf Of Gary Martin
Sent: 23 November 2009 19:36
To: [login to unmask email]
Subject: [DB2-L] Estimate EDM_SKELETON_POOL size for V9 migration?

We had a rude awakening after migrating a busy subsystem to V9 CM.
Once the workload increased to prime-time levels, we saw performance degradation with these symptoms:
. I/O delays on SPT01
. high # of PKG Loads
We had relied on the install clist calculation for EDM_SKELETON_POOL of 10MB, but after a few painful hours of troubleshooting, increased it to 100MB. This made a significant improvement in reducing PKG Loads.
We've subsequently increased it 120MB for another incremental performance improvement.

Has anyone else suffered this experience?
I'm wondering what process you are using to estimate the size of this pool?

I've since seen the recommendation to size EDM_SKELETON_POOL at least as large as V8 EDM Pool SKCT & SKCT while under peak load. I'm curious to know if other techniques have been used & how effective they have been.

Thanks,
Gary

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