Re: log file sync Wait

First of all I'd like to have the full picture of your performance: Log file sync might be 57% of the wait time, but how much of the response time is wait time?

Second, Log File Sync means Commit; So if your system is waiting a lot for commits there are two things you can do: Fewer commits (changes to applications) or faster commits (hardware striping, etc.).

No changes to the log buffer will help here (except perhaps making it smaller, as Connor McDonald so brilliantly showed during the funniest presentation I've ever seen in my life at UKOUG in Birmingham). If the log buffer is being flushed constantly, it's better to make it small so that it doesn't have to go through the whole thing every time.

Mogens

VIVEK_SHARMA wrote:

>What ALL may be Done to Address the Following ?
>Any /etc/system , init.ora parameter Changes too ?
>Moving the Online Redo Logfiles onto RAID 1 NOT possible as that may warrant Additional Hardware . Moreover T3+ does NOT Support RAID 1 (Only RAID 1+ )
>
>
>Concurrent Oracle processes = 1500 Approx.
>Statspack Taken during Mostly OLTP Operations :-
>
>Top 5 Wait Events
>~~~~~~~~~~~~~~~~~ Wait % Total
>Event Waits Time (cs) Wt Time
>-------------------------------------------- ------------ ------------ -------
>log file sync 970,563 2,597,831 57.46
>log file parallel write 831,141 484,948 10.73
>
>log_buffer = 2MB
>Online Redo Logfiles Exist on RAID 1+
>Storage Box is T3+
>File System = UFS
>
>Application = Banking (Hybrid )
>Oracle 8.1.7.4
>Solaris 8
>Machine Box = SF6800
>
>
>
>

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