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

Date: Sun, 24 Feb 2008 21:33:28 +0530
Message-ID: <>

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 [] Sent: Sunday, February 24, 2008 4:42 PM
To: VIVEK_SHARMA; Subject: RE: High "log buffer space" wait in BATCH Type Transactions

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?


Asif Momen

VIVEK_SHARMA <> 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.

Solaris 10

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Received on Sun Feb 24 2008 - 10:03:28 CST

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