How To Fix DB11176 - Wait event 'free buffer waits'

SAP Error Message - Details

• Message type: E = Error

• Message class: DB11 - Oracle Monitor: messages

• Message number: 176

• Message text: Wait event 'free buffer waits'

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message DB11176 - Wait event 'free buffer waits' ?

  The SAP error message DB11176, which indicates a wait event for "free buffer waits," typically arises in the context of database performance issues, particularly with Oracle databases. This wait event occurs when a process is waiting for a free buffer in the database's buffer cache. Here’s a breakdown of the cause, potential solutions, and related information:
  Cause
  
  Insufficient Buffer Cache: The most common cause of "free buffer waits" is that the buffer cache is too small to accommodate the workload, leading to contention for free buffers.
  High Database Load: A sudden increase in database activity can lead to more processes competing for buffer space.
  Inefficient SQL Queries: Poorly optimized SQL queries can lead to excessive buffer usage, causing contention.
  Frequent Checkpointing: If the database is performing frequent checkpoints, it can lead to a temporary shortage of free buffers.
  Memory Configuration Issues: Incorrect memory settings for the database instance can lead to inadequate buffer cache allocation.
  
  Solutions
  
  
  Increase Buffer Cache Size: 
  
  Adjust the DB_CACHE_SIZE parameter in the Oracle database to allocate more memory to the buffer cache. This can help reduce the wait times for free buffers.
  Monitor the buffer cache hit ratio to determine if the increase is effective.
  
  
  
  Optimize SQL Queries: 
  
  Review and optimize SQL queries to reduce their resource consumption. Use tools like the SQL Tuning Advisor to identify and fix inefficient queries.
  
  
  
  Monitor and Adjust Checkpointing: 
  
  Review the checkpoint settings and adjust them if necessary. Reducing the frequency of checkpoints can help alleviate buffer contention.
  
  
  
  Database Load Management: 
  
  If possible, distribute the load more evenly across the database. This can involve scheduling heavy batch jobs during off-peak hours.
  
  
  
  Use Automatic Memory Management (AMM): 
  
  If you are using Oracle, consider enabling Automatic Memory Management, which allows the database to dynamically adjust memory allocation based on workload.
  
  
  
  Monitor Wait Events: 
  
  Use Oracle's performance monitoring tools (like AWR reports) to analyze wait events and identify trends or spikes in buffer waits.
  
  
  
  Related Information
  
  Oracle Documentation: Refer to Oracle's documentation for detailed explanations of wait events and performance tuning.
  SAP Notes: Check SAP Notes related to database performance issues for specific recommendations and patches.
  Performance Monitoring Tools: Utilize tools like Oracle Enterprise Manager or third-party monitoring solutions to keep track of database performance metrics.
  
  Conclusion
  Addressing the "free buffer waits" issue involves a combination of increasing buffer cache size, optimizing SQL queries, and monitoring database performance. Regular performance tuning and monitoring can help prevent this issue from occurring in the future.