Oracle log buffer optimization techniques
 

 

Overview of redo log tuning

The steps for tuning redo log performance are straightforward:

1 - Determine the optimal sizing of the log_buffer.

2 - Size online redo logs to control the frequency of log switches and minimize system waits.

3 - Optimize the redo log disk to prevent bottlenecks.  In high-update databases, no amount of disk tuning may relieve redo log bottlenecks, because Oracle must push all updates, for all disks, into a single redo location.

 

Once you have optimized your redo and I/O sub-system, you have few options to relieve redo-induced contention.  This can be overcome by employing super-fast solid-state disk for your online redo log files, since SSD has far greater bandwidth than platter disk.

Optimizing the log_buffer region

The log_buffer is one of the most complex of the Oracle RAM region parameters to optimize, but it's a low-resource parameter (only using a few meg of RAM), so the goal in sizing log_buffer is to set a value that results in the least overall amount of log-related wait events. 

The big issue with the log buffer is determining the optimal sizing for the log_buffer in a busy, high-DML database. Common wait events related to a too-small log_buffer size include high "redo log space requests" and a too-large log_buffer may result in high "log file sync" waits.

Read more about Oracle log buffer optimization techniques here:

http://dba-oracle.com/t_log_buffer_optimal_size.htm

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