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Home -> Community -> Mailing Lists -> Oracle-L -> RE: fast_start_io_target -- which buffer?
Scott - You win! Your virtual prize is the adulation of your peers. Maybe
technically the answer would be startup after a normal shutdown.
This may be a good one for the "Oracle Myths" list. Earlier a checkpoint did flush all dirty buffers to disk, but this caused too much overhead. So Oracle no longer does that as a part of checkpoint. But many people still think it does. As Ganesh correctly points out, there are even circumstances where Oracle will write dirty data blocks to disk before the transaction commits. The reason for that is to free up data buffers for other blocks.
Thanks for the replies. All credit for the correct answer goes to the great John Hibbard, Oracle Education Instructor extraordinare.
Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Monday, April 07, 2003 5:10 PM
To: Multiple recipients of list ORACLE-L
At startup????
At 01:53 PM 4/7/03 -0800, you wrote:
>Nick - Data buffers. Specifically dirty data buffers (modified). The Oracle
>secret to high transaction throughput is that it never writes anything to
>disk until to optimum time. An Oracle trivia question (as in OCP trivia) is
>"when does the Oracle data buffer contain no dirty buffers?".
>
>
>
>Dennis Williams
>DBA, 40%OCP, 100% DBA
>Lifetouch, Inc.
>dwilliams_at_lifetouch.com
>
>-----Original Message-----
>Sent: Monday, April 07, 2003 4:04 PM
>To: Multiple recipients of list ORACLE-L
>
>
>
>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.
>BM_434315
>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.
>BM_434316
>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
>
>
>
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: DENNIS WILLIAMS
> INET: DWILLIAMS_at_LIFETOUCH.COM
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Scott Stefick INET: sstefick_at_harpercollege.edu Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: DENNIS WILLIAMS INET: DWILLIAMS_at_LIFETOUCH.COM Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Tue Apr 08 2003 - 12:34:14 CDT
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