Message-ID: <F001.0058FB80.20030505091704@fatcity.com>
Date: Mon, 05 May 2003 09:17:04 -0800
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From: "Gogala, Mladen" <MGogala@oxhp.com>
Subject: RE: log file sync wait 
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We're not talking about "_disable_logging", an ancient parameter
for cheating on benchmarks, are we? I've tried that and if anything
happens, the database doesn't come up. Other then the possibility 
that you might lose all your data, everything works fine and the
database is flying like a greased lightning.

Mladen Gogala
Oracle DBA
Phone:(203) 459-6855
Email:mgogala@oxhp.com


-----Original Message-----
Sent: Monday, May 05, 2003 5:07 AM
To: Multiple recipients of list ORACLE-L


Ganesh:

Not very true. Slower log files with bigger log buffers are the main
cause for log file sync waits. THis typically happens during a
transaction end, either commit or rollback will make others wait for
the log file sync.

To reduce this, you can keep the redo logs in the fastest disk, use
no-logging wherever you can, reduce the commits,tune the
sessions/processes parameter. And also there is an underscore parameter
which will completely eliminate the log_file_sync waits. But that is
against the Oracle's implementation of the ACID property in the
transactional database system. You can use them during batch loads,
benchmarks, _non_ production systems and test systems. But then the
committed transactions are not necessarily committed transactions.


--- ganesh_raja@non.agilent.com wrote:
> Ur Log file sync wait is mainly because your Log Buffer is small and
> every time Logwr Writes the redo into the Redo Logs your apps are
> waiting for the sync to complete. 
> 
> Run Your Lgwr in Parallel using IO Slaves or use Async_IO  parameter
> ro control it from OS.
> Increase the size of your LOGBuffer so that the ur App does not wait
> for the syncs..
> 
> HTH
> 
> Best Regards,
> Ganesh R

=====
Have a nice day !!
------------------------------------------------------------
Best Regards,
K Gopalakrishnan,
Bangalore, INDIA.
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Author: K Gopalakrishnan
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