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RE: What block size are you using for your new 9i data warehouse?

From: Todd Carlson <tcarlson_at_tripos.com>
Date: Fri, 26 Apr 2002 13:00:58 -0800
Message-ID: <F001.004510E4.20020426130058@fatcity.com>


If I remember right the default W2K block size is .5K. The max IO size depends on the RAID controllers used.

What, you don't like the GUI? ;-)

Todd Carlson
Oracle Database Administrator
Tripos, Inc.
(314) 647-8837 Ext.3246

-----Original Message-----
Lisa
Sent: Friday, April 26, 2002 3:31 PM
To: Multiple recipients of list ORACLE-L warehouse?

Can anyone tell me how to figure out the file system block size and max i/o
size of a Windows 2000 system? My sysadmin had no clue. (Gosh, can't imagine why, everything's hidden behind that stupid gui)

Thanks in advance for any replies

Lisa Koivu
Oracle Database Baby Oven
Fairfield Resorts, Inc.
5259 Coconut Creek Parkway
Ft. Lauderdale, FL, USA 33063

> -----Original Message-----
> From: Gaja Krishna Vaidyanatha [SMTP:oraperfman_at_yahoo.com]
> Sent: Friday, April 26, 2002 12:49 PM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: What block size are you using for your new 9i data
> warehouse?
>
> All,
>
> Something to keep in mind regardless of whether you
> are using 9i or not. This issue becomes more relevant
> in 9i with "multiple block sizes" for different
> tablespaces.
>
> You always want to ensure that your DB_BLOCK_SIZE =
> File System Block Size. This is to avoid wasted I/O
> and also the case where the "read ahead algorithm" is
> triggered accidentally, when 1 Database Block results
> in multiple file system blocks being read from disk.
>
> If your application performs range scans, there is a
> high possibility that multiple "single database block"
> read requests to a set of contiguous blocks, may
> result in the "read ahead algorithm" performing 128K
> or 256K pre-fetches, even though your application may
> have not required all 128K or 256K.
>
> This problem is rampant on ufs file systems where the
> default block size is 512 bytes, and with a 8K
> DB_BLOCK_SIZE, it takes 16 file system blocks to store
> 1 DB block on disk. However, even if you have advanced
> file systems and have a 1-is-to-2 ratio of DB block
> is-to FS blocks, you are still in danger of
> overloading your I/O sub-system, "under the right
> conditions".
>
> If you are using a volume manager product such as
> Veritas, and if your version of the volume manager
> supports "dynamic file system block sizing" based on
> size of the file system or the files themselves,
> please pay close attention to that detail and make
> sure that the file system block size does not exceed
> the database block size (based on the size of the file
> system).
>
> Best regards,
>
> Gaja
>
> --- Johnson Poovathummoottil <joni_65_at_yahoo.com>
> wrote:
> > We too have a data warehouse close to 500GB in size.
> > We upgraded the OS solaris 2.8 and our block size is
> > 16K. All our data and index tablespaces datafiles
> > are
> > spread across 20 files systems whose disks are on
> > EMC
> > storage. We too user veritas volume manager. File
> > systems use four 9 GB disks whaich are raid S and
> > software stripe uinit size of 256 KB.
> >
> > reasons
> > 16K block size as we have many full table scan ans
> > sequential reads.
> > 256 KB stripe unit size because we have set the
> > db_file_multi_block_read_count to 64(1MB)
> >
> > we are moving to a sun fire 15K machine soon and
> > then
> > the we will go to 9i 64 bit.
> >
> > --- "Toepke, Kevin M" <ktoepke_at_trilegiant.com>
> > wrote:
> > > Cherie:
> > >
> > > If you are using Oracle 9i, you can use mutliple
> > > block sizes! You still
> > > create your database with a default block size,
> > but
> > > each tablespace (except
> > > system) can have a block size different from the
> > > default.
> > >
> > > Valid blocksizes are limited by OS, but they range
> > > from 2K to 32k.
> > >
> > > Check out the 9i docs for CREATE TABLESPACE for
> > more
> > > info.
> > >
> > > Caver
> > >
> > > -----Original Message-----
> > > Sent: Thursday, April 25, 2002 11:24 AM
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > >
> > > We are building a new version 9.0.1 data warehouse
> > > on Sun Solaris 2.6
> > > migrating to Solaris 2.8. We will be using
> > striped
> > > disk that is striped
> > > using Veritas Volume Manager on EMC disk.
> > >
> > > The datawarehouse will be about 200 Gig. It will
> > > be written to throughout
> > > the day.
> > >
> > > To this point, almost all of our databases have
> > been
> > > created with an 8k
> > > block size. i'm not sure if that blocksize is
> > > optimal anymore. With 9i,
> > > what block sizes are people using in the field
> > > nowadays for data
> > > warehouses?
> > >
> > > Also, if you use striped disk, what stripe size
> > are
> > > you using and why?
> > >
> > > Thanks for weighing in on this topic.
> > >
> > > Cherie Machler
> > > Oracle DBA
> > > Gelco Information Network
> > >
> > > --
> > > Please see the official ORACLE-L FAQ:
> > > http://www.orafaq.com
> > > --
> > > Author:
> > > INET: Cherie_Machler_at_gelco.com
> > >
> > > Fat City Network Services -- (858) 538-5051
> > FAX:
> > > (858) 538-5051
> > > San Diego, California -- Public Internet
> > > access / Mailing Lists
> > >
> >
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> >
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>
> =====
> Gaja Krishna Vaidyanatha
> Director, Storage Management Products,
> Quest Software, Inc.
> Co-author - Oracle Performance Tuning 101
> http://www.osborne.com/database_erp/0072131454/0072131454.shtml
>
> __________________________________________________
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Gaja Krishna Vaidyanatha
> INET: oraperfman_at_yahoo.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Koivu, Lisa
  INET: lisa.koivu_at_efairfield.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Todd Carlson
  INET: tcarlson_at_tripos.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
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also send the HELP command for other information (like subscribing).
Received on Fri Apr 26 2002 - 16:00:58 CDT

Original text of this message

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