How To Fix HH047 - Check the values of 'page cleaner' and 'LRU_MAX_DIRTY'

SAP Error Message - Details

• Message type: E = Error

• Message class: HH - (Long) text for check tool 'infcfgcheck'

• Message number: 047

• Message text: Check the values of 'page cleaner' and 'LRU_MAX_DIRTY'

What causes this issue?

This is a single 'performance' check and therefore does not
describe a critical system status. It is neither necessary nor
time-critical to perform the steps described below, but they could
help improve the overall performance of your R/3 System.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

'Foreground writes' occurred since the last time you started the
database. A 'foreground write' is necessary if an Informix user
thread (' light-weight process) does not find an empty or unmodified
buffer in Shared Memory therefore buffers have to be 'emptied' to
disk. This is very time-consuming and should be avoided if possible.

System Response

How to fix this error?

Check the number of 'page cleaners' (ONCONFIG parameter 'CLEANERS')
and ONCONFIG parameter 'LRU_MAX_DIRTY' after reading Note 41360.
To change an ONCONFIG parameter, edit the file
'$INFORMIXDIR/etc/$ONCONFIG' as user 'informix'.
CAUTION: The change will only become active when the database has
been started up.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message HH047 - Check the values of 'page cleaner' and 'LRU_MAX_DIRTY' ?

  The SAP error message HH047 indicates an issue related to the database buffer management, specifically concerning the parameters 'page cleaner' and 'LRU_MAX_DIRTY'. This error typically arises in the context of SAP HANA or other database systems where memory management and data consistency are critical.
  Cause:
  
  
  Page Cleaner: The page cleaner is responsible for writing dirty pages (modified data) from the memory to the disk. If the page cleaner is not functioning correctly or is misconfigured, it can lead to performance issues or data consistency problems.
  
  
  LRU_MAX_DIRTY: This parameter defines the maximum number of dirty pages that can be held in memory. If this limit is reached, it can prevent new data from being written to memory, leading to potential errors or performance degradation.
  
  
  Solution:
  
  
  Check Configuration: Review the configuration settings for the page cleaner and LRU_MAX_DIRTY. Ensure that they are set to appropriate values based on your system's workload and memory capacity.
  
  
  Increase LRU_MAX_DIRTY: If the LRU_MAX_DIRTY value is too low, consider increasing it to allow more dirty pages in memory. This can help improve performance by reducing the frequency of writes to disk.
  
  
  Monitor Page Cleaner Activity: Use monitoring tools to check the activity of the page cleaner. Ensure that it is running efficiently and not being throttled or encountering errors.
  
  
  Database Maintenance: Regularly perform database maintenance tasks, such as cleaning up old data, optimizing tables, and ensuring that the database is not overloaded with unnecessary data.
  
  
  Consult Documentation: Refer to the SAP documentation or the specific database documentation for detailed guidance on configuring these parameters.
  
  
  System Resources: Ensure that your system has adequate resources (CPU, memory, disk I/O) to handle the workload. If resources are constrained, consider upgrading hardware or optimizing the application.
  
  
  Related Information:
  
  SAP Notes: Check for any relevant SAP Notes that may provide additional insights or patches related to this error.
  Performance Monitoring: Utilize SAP's performance monitoring tools to analyze the database's performance and identify bottlenecks.
  Database Logs: Review database logs for any additional error messages or warnings that may provide context for the HH047 error.
  Consult SAP Support: If the issue persists after making adjustments, consider reaching out to SAP support for further assistance.
  
  By addressing the configuration and monitoring the performance of the page cleaner and LRU_MAX_DIRTY, you can mitigate the issues related to the HH047 error message.