IDS Forum

Re: Tips to reduce the IO times / alice hot list o

Posted By: Art Kagel
Date: Thursday, 9 July 2009, at 12:31 p.m.

In Response To: Tips to reduce the IO times / alice hot list optim (Alexandre Marini)

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
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

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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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