Self tuning bufferpool

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dunleav1 - 26 Sep 2008 19:26 GMT

In 9.1 and 9.5 (Linux 64 bit) when a buffer pool is set to self-
tuning, how are blocks configured in respect to blocked vs non-blocked
when self-tuning is set to on?

(ie) I have one bufferpool that is 16k that the IBMDEFAULTBP is shared
between all tablespaces.
The data tablespace has prefetch automatic set to on.

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Ian - 26 Sep 2008 20:15 GMT

> In 9.1 and 9.5 (Linux 64 bit) when a buffer pool is set to self-
> tuning, how are blocks configured in respect to blocked vs non-blocked
[quoted text clipped - 3 lines]
> between all tablespaces.
> The data tablespace has prefetch automatic set to on.

STMM will not tune the size of the block-based area of a bufferpool.

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dunleav1 - 29 Sep 2008 18:26 GMT

> > In 9.1 and 9.5 (Linux 64 bit) when a buffer pool is set to self-
> > tuning, how are blocks configured in respect to blocked vs non-blocked
[quoted text clipped - 5 lines]
>
> STMM will not tune the size of the block-based area of a bufferpool.

I can't seem to set a block based area in a bufferpool that is self
tuning.
I can't set a large initial size for the bufferpool area either. When
I set a size and recycle the database, the
initial size defaults back to 1000 16k when using self tuning.

Isn't it possible to allocate a larger initial bufferpool area, and to
use block-based bufferpools when using self tuning memory?

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Ian - 29 Sep 2008 20:06 GMT

> I can't seem to set a block based area in a bufferpool that is self
> tuning.

create bufferpool bp
    size 100000 automatic
    numblockpages 1000
    pagesize 4096

> I can't set a large initial size for the bufferpool area either. When
> I set a size and recycle the database, the
> initial size defaults back to 1000 16k when using self tuning.

alter bufferpool yourbp size 100000 automatic numblockpages 1000

Keep in mind, DB2 may reduce the size of the bufferpool if it doesn't
see demand for it.

> Isn't it possible to allocate a larger initial bufferpool area, and to
> use block-based bufferpools when using self tuning memory?

Yes. But as I said, the number of block pages is fixed when the
bufferpool is allocated. So, while STMM may grow (and shrink) the
size of the page-based area of the bufferpool, the block-based
area will remain fixed.

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