IDS Forum

Re: Tips to reduce the IO times / alice hot li....

Posted By: Alexandre Marini
Date: Thursday, 9 July 2009, at 1:18 p.m.

In Response To: Re: Tips to reduce the IO times / alice hot list o (Art Kagel)

Ok, thanks Art.
There reminds me of doing another question kkkkkkkk.
There could be any improve on our IO performance, if we try to optimize
our BUFFERPOOL settings?
now we have:
BUFFERPOOL
size=2K,buffers=100000,lrus=128,lru_min_dirty=50.000000,lru_max_dirty=60.000000
BUFFERPOOL
size=16K,buffers=500000,lrus=80,lru_min_dirty=65.000000,lru_max_dirty=80.000000

Since the non-transactional databases are on 16Kb pagesizes,
what does the lrus parameter could impact on performance? Or just it
impact memory usage, really?
Our lru initial values are even "hard" enough or if we increse it to
70.0 / 90.0 we could impact some performance?

Obs: on our OLTP instance, a simple adjust on our BTSCANNER raised our
idle times to 95 % averages!

Regards for your quality technical answers.... it´s always a tech
"bible" for us!

Alexandre Marini

Analista de Tecnologia da Informação - DBA

SEFAZ-MS / SGI-UIMP / Sistemas IBM-Informix

Art Kagel escreveu:
> This is a DW system so I'm guessing rather few deletes. Therefore the
> BTSCANNERs aren't doing much at all, hence the rather empty onstat -C
> report. Mine looks like:
>
> $ onstat -C
>
> IBM Informix Dynamic Server Version 11.50.FC3X6 -- On-Line -- Up 4 days
> 04:20:15 -- 48472 Kbytes
>
> B-tree Scanner Information
> Profile
> =======
> Active Threads 1
> Global Commands 2000000 Building hot list
> Number of partition scans 4132
> Main Block 0x0000000045721d68
> BTC Admin 0x0000000044c2a2f8
>
> BTS info id Prio Partnum Key Cmd
> 0x45bfea68 0 High 0x00000000 0 40 Yield N
>
> Number of leaves pages scanned 471
>
> Number of leaves with deleted items 53
>
> Time spent cleaning (sec) 0
>
> Number of index compresses 7
>
> Number of deleted items 4176
>
> Number of index range scans 0
>
> Number of index leaf scans 1
>
> Number of index alice scans 7
>
> And that's on a sndbox instance with not much activity. Your beating a dead
> horse I think.
>
> Art
>
> Art S. Kagel
> Oninit (www.oninit.com)
> IIUG Board of Directors (art@iiug.org)
>
> Disclaimer: Please keep in mind that my own opinions are my own opinions and
> do not reflect on my employer, Oninit, the IIUG, nor any other organization
> with which I am associated either explicitly or implicitly. Neither do
> those opinions reflect those of other individuals affiliated with any entity
> with which I am affiliated nor those of the entities themselves.
>
> On Thu, Jul 9, 2009 at 12:16 PM, Alexandre Marini <amarini@fazenda.ms.gov.br
>
>> wrote:
>>
>
>
>> Hello, friends.
>> I´ve got a question on our 11.50.FC4 instance, running on a linux 64
>> red-hat based instance.
>> (Obs: this is an OLAP system - DW based, so it´s not transactional)
>>
>> We´ve configured the BTSCANNER settings to use alice mode, but our IO is
>> even 87% average (idle time).
>> Our actual configs are:
>> BTSCANNER num=4,threshold=900,rangesize=-1,alice=9,compression=high
>>
>> Our machine has 8 cores, 4 * dual core,
>> and 7 cpu vps, 3 aio, 1 lio, and 1 pio also.
>>
>> How can I try to lower our idle times, since alice is level 9 already,
>> and our hotlist is:
>> B-tree Scanner Information
>>
>> Index Hot List
>> ==========================================
>>
>> Current Item 3 List Created 12:01:00
>>
>> List Size 2 List expires in 0 sec
>>
>> Hit Threshold 1000 Range Scan Threshold -1
>>
>> Partnum Key Hits
>> 0x001001CD 1 2143 *
>> 0x001001CE 1 2143 *
>> ==========================================
>> Obs: I´d even tryed to change the "onmode -C [duration]" time,
>> but the "List expires" is always in 0 seconds, like above.
>>
>> Regards for all.
>>
>> --
>>
>> Alexandre Marini
>>
>> Analista de Tecnologia da Informação - DBA
>>
>> SEFAZ-MS / UIMP / Sistemas: Fronteiras e SIG-DW
>>
>>
>>
>>
>>
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Messages In This Thread

• Tips to reduce the IO times / alice hot list optim
  Alexandre Marini -- Thursday, 9 July 2009, at 12:16 p.m.
  • Re: Tips to reduce the IO times / alice hot list o
    Art Kagel -- Thursday, 9 July 2009, at 12:31 p.m.
    • Re: Tips to reduce the IO times / alice hot li....
      Alexandre Marini -- Thursday, 9 July 2009, at 1:18 p.m.

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