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Use

Avg write time <duration> ms for <number_of> writes (<number_of> pages) on volume <volume_name>


Explanation

A high number of writes will be necessary in case of long load times (data import), because the imported data is usually much larger than the size of the data cache.

Generally, if the data cache is not big enough, data must be displaced from the data cache to the data area, which means that there might be a large number of writes to the data volumes. Furthermore high write activity can be observed when savepoints are written as this causes cache content to be flushed on the volumes. 

For modern disks the write times should not exceed 20 ms.

Currently you will often find high priority warnings related to just a few write operations. If there is a high duration for just a few writes, it is usually not critical.

User Response

If you observe high write times related to a high amount of I/O you should check the disk architecture.
 

More Information

Relevant  DB-Analyzer FilesHelpful with ...
DBAN_IO.csv  Read and write operations to cache pages and data pages 
DBAN_IOTHREADS.csv Number and duration of physical write and read operations (I/O threads) 
SAP Notes 
  
Expert SessionsContent / Helpful with ...
Session 26: SAP MaxDB I/O Concept   
Documentation (links) 
  
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