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Re: fast_start_io_target -- which buffer?

From: Stephane Faroult <sfaroult_at_oriole.com>
Date: Mon, 07 Apr 2003 13:34:57 -0800
Message-ID: <F001.0057C58B.20030407133457@fatcity.com>


> Nick Wagner wrote:
>
> according to the Oracle documentation for FAST_START_IO_TARGET...
>
> ----------------------------------------
> Set this parameter to n, where n is an integer limiting to n the
> number of "buffers" that Oracle processes during crash or instance
> recovery. Because the number of I/Os to be processed during recovery
> correlates closely to the duration of recovery, the
> FAST_START_IO_TARGET parameter gives you the most precise control over
> the duration of recovery.
>
> FAST_START_IO_TARGET advances the checkpoint, because DBWn uses the
> value of FAST_START_IO_TARGET to determine how much writing to do.
> Assuming that users are making many updates to the database, a low
> value for this parameter forces DBWn to write changed "buffers" to
> disk. As the changed "buffers" are written to disk, the checkpoint
> advances.
>
> The smaller the value of FAST_START_IO_TARGET, the better the recovery
> performance, because fewer blocks require recovery. If you use smaller
> values for this parameter, however, then you impose higher overhead
> during normal processing, because DBWn must write more buffers to disk
> more frequently.
> -----------------------------------------
>
> My question... which "buffers" are they referring to here? The log
> buffer?
>
> Thanks!!
>
> Nick
>

As I understand it, the usual DB block buffers - written by DBWR but reconstructed (hence the quotes) from the redolog files.

-- 
Regards,

Stephane Faroult
Oriole Software
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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Received on Mon Apr 07 2003 - 16:34:57 CDT

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