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Re: DBWR write chunk

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 2 Feb 2001 18:53:18 -0000
Message-ID: <981140157.27889.1.nnrp-01.9e984b29@news.demon.co.uk>

This is the number of blocks that dbwr
will attempt to find and write when called by a process that needs some buffers
freed. It does not imply anything about continuous buffers, or single write sizes.

In some versions of Oracle, it can be set by the value of _db_block_write_batch.

--
Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Practical Oracle 8i:  Building Efficient Databases
Publishers:  Addison-Wesley

Reviews at: http://www.jlcomp.demon.co.uk/book_rev.html



argosy22_at_my-deja.com wrote in message <95eqsl$9bs$1_at_nnrp1.deja.com>...

>HI all,
>
>I run this query in Oracle 8.1.7 and get info
>on the DBWR write chunk:
>
>
>Select *
>from X$KVII
>
>
>ADDR INDX INST_ID KVIIVAL KVIITAG
> KVIIDSC
>-------- ---------- ---------- ----------
>--------------------------------------
>--------------------------
>-----------------------------------------------------
>-----------
>
>
>093D9490 6 1 160 kcbscw
> DBWR write chunk
>
>
>The OS block size is: 512 bytes.
>512 / 160 = 3.2
>
>The DB_BLOCK_SIZE is 8K (8192)
>8192 / 160 = 51.2
>
>
>These are uneven numbers, meaning that the drives would
>be working too hard if they were writing in chunks
>of 160 bytes.
>
>
>
>If this was in kilobytes, then this would divide evenly.
>
>160K / 8K = 20
>
>But the odd thing is that the smallest extents that I have
>created are 128K.
>
>
>Where can I find more info on this parameter? What is it
>measured in? Bytes? Is it possible to modify it? How?
>
>Thanks
>
>
>Sent via Deja.com
>http://www.deja.com/
Received on Fri Feb 02 2001 - 12:53:18 CST

Original text of this message

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