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Re: fast_start_io_target -- which buffer?

From: Scott Stefick <>
Date: Mon, 07 Apr 2003 13:58:50 -0800
Message-ID: <>

No, I think they are referring to the Data buffer Cache buffers. My understanding is that when data is changed, DBWn writes to a data block buffer in the Buffer Cache, and LGWR writes the before and after data to the Redo Log Buffer. Then for instance, at a checkpoint, the DBWn writes out it's dirty buffers from the buffer cache to the datafiles and LGWR writes to the logfiles.


At 01:03 PM 4/7/03 -0800, you 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
>My question... which "buffers" are they referring to here? The log buffer?

Scott Stefick
Systems / Oracle Certified DBA
Wm. Rainey Harper College
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Author: Scott Stefick

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Received on Mon Apr 07 2003 - 16:58:50 CDT

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