difference between data cache and buffer pool

[samuel]

hello

what is the difference between data cache and buffer pool is
ase?

I am bit confused about both.

Also, how to increase the size of each?
how to create a new buffer pool? and how to remove this
buffer pool?

thank you.

[Bret Halford [Sybase]]

A buffer pool is a subset of a data cache. Each data cache
can have up to 4 buffer pools, one each for 1 page, 2 page, 4 page
and 8 page i/os.

Use sp_poolconfig and sp_cacheconfig to administer them.

-bret

[Samuel]

Bret thank you for your answer.

I have the default data cache already set to 8G (that was
the max that I can set).

I want to create a 16k buffer pool

sp_poolconfig 'default data cache','2000M','16K'

now i have

IO Size Wash Size Config Size Run Size APF Percent
-------- ------------- ------------ ------------
-----------
4 Kb 122880 Kb 0.00 Mb 6192.00 Mb 10
16 Kb 122880 Kb 2000.00 Mb 2000.00 Mb 10

what does this mean?
how to remove again this new pool?
thank you.

[Jayadeva]

> Bret thank you for your answer.
>
> I have the default data cache already set to 8G (that was
> the max that I can set).
>
> I want to create a 16k buffer pool
>
> sp_poolconfig 'default data cache','2000M','16K'
>
> now i have
>
> IO Size Wash Size Config Size Run Size APF
> Percent
> -------- ------------- ------------ ------------
> -----------
> 4 Kb 122880 Kb 0.00 Mb 6192.00 Mb 10
> 16 Kb 122880 Kb 2000.00 Mb 2000.00 Mb 10
>
> what does this mean?

If no large I/O memory pools exist in a cache, Adaptive
Server performs I/O in logical page size units, the size of
a data page, for all of the objects bound to the cache. You
can often enhance performance by configuring pools that
perform large I/O. A 16K memory pool reads and writes eight
data pages in a single I/O for a 2K logical page size
server.

Refer sybooks to find more about this.

> how to remove again this new pool?

sp_poolconfig 'default data cache','0M','16K'

> thank you.
>
> > samuel wrote:
> > > hello
> > >
> > > what is the difference between data cache and buffer
> > > pool is ase?
> > >
> > > I am bit confused about both.
> > >
> > > Also, how to increase the size of each?
> > > how to create a new buffer pool? and how to remove
> > > this buffer pool?
> > >
> > > thank you.
> >
> > A buffer pool is a subset of a data cache. Each data
> > cache can have up to 4 buffer pools, one each for 1 page

> > , 2 page, 4 page and 8 page i/os.

[Carl Kayser]

"Sherlock, Kevin [TeamSybase]" <kevin.s...@teamsybase.com> wrote in
message news:49491ffd$1@forums-1-dub...
> It means that you created and ASE server with 4k pages (instead of the
> default 2k pages). That's not a problem of course, just a conscious
> decision on your part to have a 4k ASE server.
>
> pools within a cache on a 4K ASE server can have sizes of 1 page (4k),
> 2pages (8k), 4 pages (16k) and 8 pages (32k). You chose to create a 4
> page (16k) pool in your default data cache. Each data cache is REQUIRED
> to have a 1 page (4k) pool. Each cache can have additional pools, but it
> is usually only effective to have only one large pool (ie, a 2,4, or 8
> page pool).
>

As I remember, by default, the 2 page pool will be used by transaction logs.
Otherwise only the smallest (1 page) and largest pool sizes will be used
(per each cache). Anything else is unused (i.e., wasted memory).

[Sherlock, Kevin [TeamSybase]]

It means that you created and ASE server with 4k pages (instead of the
default 2k pages). That's not a problem of course, just a conscious
decision on your part to have a 4k ASE server.

pools within a cache on a 4K ASE server can have sizes of 1 page (4k),
2pages (8k), 4 pages (16k) and 8 pages (32k). You chose to create a 4 page
(16k) pool in your default data cache. Each data cache is REQUIRED to have
a 1 page (4k) pool. Each cache can have additional pools, but it is usually
only effective to have only one large pool (ie, a 2,4, or 8 page pool).

If you want to drop your 16k pool and give that memory back to your 4k pool,
simply modify the 4k pool to "steal" back the 16k pool memory:

sp_poolconfig 'default data cache','8192M','4K','16K'

As for the question of "what does this mean?" , I assume you want to know
what large io pools are used for. That is best explained in the manuals.

such as
http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.dc20020_1251/html/databases/X25924.htm
and many other references to data cache planning/tuning etc in the PT guide.

<Samuel> wrote in message news:494821aa.5cd...@sybase.com...

[Derek Asirvadem]

> On 2008-12-18 03:03:50 +1100, "Carl Kayser" <kays...@bls.gov> said:

Yeah, but I wouldn't pu it that way.
The tran logs use the sp_logiosize pool (and true, most of us set it to
2 pages), unless it is bound to its own cache (which should have only
that pool).

I agree anything other than the smallest and largest poolsize within a
cache, is unused.
--
Regards
Derek Asirvadem
Director / Senior Sybase DBA / Information Architect
Sybase BSA [OEM/VAR] Partner
Copyright © 2008 Software Gems Pty Ltd