RE: High "log buffer space" wait in BATCH Type Transactions

  • From: VIVEK_SHARMA <VIVEK_SHARMA@xxxxxxxxxxx>
  • To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Sun, 24 Feb 2008 06:54:19 +0530


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.

Solaris 10

Will Share Statspack as needed please.

Cheers & Thanks


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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