RE: High "log buffer space" wait in BATCH Type Transactions
- From: Asif Momen <asif_oracle@xxxxxxxxx>
- To: VIVEK_SHARMA@xxxxxxxxxxx, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Sun, 24 Feb 2008 03:12:15 -0800 (PST)
Hi Vivek,
"log buffer space" wait event occurs normally when Log Writer is too slow or
when the log buffer is too small.
I think in your case LGWR is slow.
> Currently The Redo logfiles are on Mounted filesystem.
What is the OS block size of this mount point?
Did you enable CIO/DIO on this mount point?
How many redo log members do you have?
Regards
Asif Momen
http://momendba.blogspot.com
VIVEK_SHARMA <VIVEK_SHARMA@xxxxxxxxxxx> wrote:
Folks
During a Benchmark Run on Batch Type Transactions on NON-RAC Database using
Dedicated sessions following High "log buffer space" wait is seen.
NOTE - Increasing log_buffer size from 7Mb to 32 Mb only resulted in a further
REDUCED Performance.
Currently The Redo logfiles are on Mounted filesystem.
Qs Will moving the Redo back to RAW Devices also Reduce the "log buffer space"
wait wait for BATCH Runs?
NOTE - Previously, For OLTP type Transactions on the SAME Database, High "log
file sync" wait was also seen with Redo on Mounted filesystem which
disappreared when the Redo were moved to RAW Devices.
Oracle 10.2.0.3
Solaris 10
Will Share Statspack as needed please.
Cheers & Thanks
Vivek
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time
----------------------------------------- ------------ ----------- ------ ------
log buffer space 2,464,248 585,064 237 76.0
CPU time 103,594 13.5
log file sync 48,470 30,062 620 3.9
buffer busy waits 116,409 14,745 127 1.9
db file parallel write 2,102,173 14,517 7 1.9
-------------------------------------------------------------
^LHost CPU (CPUs: 120)
~~~~~~~~
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