IDS Forum

Re: BUFFERPOOL question

Posted By: jak aka
Date: Tuesday, 17 February 2009, at 10:48 p.m.

In Response To: Re: BUFFERPOOL question (John Miller iii)

Thank you all.

I have few more question.

Suppose.
buffer = 1000000

case1 lru_max = 51 , lru_min=50
case2 lru_max = 2 , lru_min=1

Dirty pages will be flushed 1% when checkpoint time (1% of 1M = 10000 pages) .
The checkpoint duration must be equal becase both case will flush only 10000 pages. Am I correct ?

- If I want to reduce the checkpoint to the mimimum duration , Can I set 0.0002, 0.0001 (lru_max,lru_min) (i'm not sure how many digit can I set) or 50.0002,50.0001 (0.0001 % of buffer to be flush when normal checkpoint) to make all dirty page flushed by lru-flush.
If I do so, Any concern would you recommend ?

Best regards,
Jakkrit A.

________________________________
From: John Miller iii <miller3@us.ibm.com>
To: ids@iiug.org
Sent: Wednesday, February 18, 2009 4:03:31 AM
Subject: Re: BUFFERPOOL question [14905]

While this answer is very accurate for IDS releases before version 11. =
In
version 11
there is a new feature called non-blocking checkpoints. In short, it i=
s
generally
beneficial to have lru min and max dirty above 50% in version 11 or hig=
her.
I
would suggest reading the following for more details.

http://www.ibm.com/developerworks/data/library/techarticle/dm-0703lashl=
ey/index.html

John F. Miller III
STSM, Support Architect
miller3@us.ibm.com
503-578-5645
IBM Informix Dynamic Server (IDS)

ids-bounces@iiug.org wrote on 02/17/2009 09:40:46 AM:

> 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 theard=
s.
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 exampl=
e,
If
> we have a have a configuration of 51,50 (max_dirty and min_dirty). Th=
e
> 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 flus=
h
dirty
> page is more efficient in checkpoint process than will cleaners
(checkpoint
> don=B4t 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 yo=
ur
> 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 Fern=E1ndez
> 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_m=
ax
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 nothi=
ng.
> >
> > 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 th=
e
> > BUFFERPOOL section. You may also find more information in the Tunin=
g
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 differe=
nt
> >> between
> >> BUFFERPOOL below ?
> >>
> >> BUFFERPOOL
> >> size=3D2K,buffers=3D1000000,lrus=3D64,lru_min_dirty=3D1,lru_max_di=
rty=3D2
> >> and
> >> BUFFERPOOL
> >> size=3D2K,buffers=3D1000000,lrus=3D64,lru_min_dirty=3D51,lru_max_d=
irty=3D52
> >>
> >> 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 a=
ny
> > 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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Forum Note: Use "Reply" to post a response in the discussion forum.

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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