RE: High "log buffer space" wait in BATCH Type Transactions
Date: Sun, 24 Feb 2008 21:33:28 +0530
Thanks Asif for responding & the advice
Redo Logfiles are being MOVED to RAW Devices to handle this wait. 6 Redo Log Groups exist with 2 Members each(Multiplexed) , size 750 MB
Storage Box is a SAN Storage - Hitachi , Storage Box Model - Sun StoreEdge - 9990
OS Block Size 8K
Stripe Unit size 64 K
Total Cache on the storage box – 128 GB
Cache Management Policy - Write Behind
CIO/DIO - am NOT sure if it is used.
From: Asif Momen [asif_oracle_at_yahoo.com] Sent: Sunday, February 24, 2008 4:42 PM
To: VIVEK_SHARMA; oracle-l_at_freelists.org Subject: RE: High "log buffer space" wait in BATCH Type Transactions
"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?
VIVEK_SHARMA <VIVEK_SHARMA_at_infosys.com> wrote:
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.
- CAUTION - Disclaimer ***************** This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify the sender by e-mail and delete the original message. Further, you are not to copy, disclose, or distribute this e-mail or its contents to any other person and any such actions are unlawful. This e-mail may contain viruses. Infosys has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachment. Infosys reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infosys e-mail system. ***INFOSYS******** End of Disclaimer ********INFOSYS*** -- http://www.freelists.org/webpage/oracle-l