IDS Forum

Re: BUFFERPOOL question

Posted By: Jorge cruces
Date: Tuesday, 17 February 2009, at 12:40 p.m.

In Response To: Re: BUFFERPOOL question (jak aka)

Informix have two different forms of flush dirty page from buffer to disck.
The first one is online (not lock) and if made by the cleaners theards. The
second one if in the checkpoint proccess (locking updates).

The form of work of the cleaners depends of the lru_min_dirty and
lru_max_dirty parameters. Lru_max_dirty parameter specify when the cleaners
began to work and lru_min_dirty when cleaners stop to work. By example, If
we have a have a configuration of 51,50 (max_dirty and min_dirty). The
cleaners not began to work until the 51% of the buffers are dirty. In your
second example if we have 2,1, the cleaners began to work when the 2% of the
buffers are dirty. Is clear than with a configuration of 2,1 we go to have
minus dirty pages when the checkpoint process start and the duration of
checkpoints will be smaller.

This sound fine, but you also must to have in consideration than flush dirty
page is more efficient in checkpoint process than will cleaners (checkpoint
don´t need to worry about locks).

So, in sumary if you have interative operations in your database your must
to have small values for lry_min_dirty and lry_max_dirty and a small
checkpoint interval in order to not lock interatives users. But if your
database only have batch operation don't worry about checkpoint times
because don't lock anyone and put high values for this parameters.

I hope this clarify you

Juan Jorge Cruces Fernández
Accelya

----- Original Message -----
From: "jak aka" <jakkritakeng@yahoo.com>
To: <ids@iiug.org>
Sent: Monday, February 16, 2009 6:27 AM
Subject: Re: BUFFERPOOL question [14893]

> Sorry , I may ask you not clear. I know what's the meaning of lru_max and
> lru_min and I 've also read many book but I still not clear. I don't want
> to
> waste your time if you feel uncomfortable to answer please do nothing.
>
> Anyway , my question is if I remain the gap 1 (lru_max - lrun_min ,2-1 ,
> 52-51) . What 's the different ?
> What will be effect, checkpoint ,... ?
>
> Sorry again Art.
>
> ________________________________
> From: Art Kagel <art.kagel@gmail.com>
> To: ids@iiug.org
> Sent: Thursday, February 12, 2009 6:35:43 PM
> Subject: Re: BUFFERPOOL question [14857]
>
> Trick question?
>
> The LRU flush parameters, lru_max_dirty and lru_min_dirty are different.
>
> If you want more than that, look in the Administrator's Reference manual
> for
> the meaning, purpose, and setting of the lru flush parameters in the
> BUFFERPOOL section. You may also find more information in the Tuning Guide
> or by searching the archives of this list for lru_min_dirty,
> lru_max_dirty,
> and lru_min/max_dirty (I sometimes refer to both together that way. Meet
> us
> half way Jak, do some research before you post a question.
>
> (*&^ but I'm cranky today.
>
> Art
>
> On Thu, Feb 12, 2009 at 2:31 AM, jak aka <jakkritakeng@yahoo.com> wrote:
>
>> Hi all,
>>
>> I have a basic question but it make me confuse. What's the different
>> between
>> BUFFERPOOL below ?
>>
>> BUFFERPOOL
>> size=2K,buffers=1000000,lrus=64,lru_min_dirty=1,lru_max_dirty=2
>> and
>> BUFFERPOOL
>> size=2K,buffers=1000000,lrus=64,lru_min_dirty=51,lru_max_dirty=52
>>
>> Best Regards,
>> Jakkrit A.
>>
>>
>>
>>
>
> *******************************************************************************
>> Forum Note: Use "Reply" to post a response in the discussion forum.
>>
>>
>
> --
> 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.
>
> --001485f91dd2b220b50462b71e68
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

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Messages In This Thread

• BUFFERPOOL question
  jak aka -- Thursday, 12 February 2009, at 2:31 a.m.
  • AW: BUFFERPOOL question
    Andreas.KUTSCHE@spar.at -- Thursday, 12 February 2009, at 6:22 a.m.
  • Re: BUFFERPOOL question
    Art Kagel -- Thursday, 12 February 2009, at 6:35 a.m.
    • Re: BUFFERPOOL question
      jak aka -- Monday, 16 February 2009, at 12:27 a.m.
      • Re: BUFFERPOOL question
        Jorge cruces -- Tuesday, 17 February 2009, at 12:40 p.m.
        • Re: BUFFERPOOL question
          John Miller iii -- Tuesday, 17 February 2009, at 4:03 p.m.
          • Re: BUFFERPOOL question
            jak aka -- Tuesday, 17 February 2009, at 10:48 p.m.
            • Re: BUFFERPOOL question
              Art Kagel -- Tuesday, 17 February 2009, at 11:06 p.m.
              • Re: BUFFERPOOL question
                jak aka -- Wednesday, 18 February 2009, at 11:05 p.m.
      • Re: BUFFERPOOL question
        Art Kagel -- Tuesday, 17 February 2009, at 7:33 p.m.
  • Re: BUFFERPOOL question
    Mark Jamison -- Friday, 13 February 2009, at 2:18 p.m.

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