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User task <task_ID>: physical writes: <count> (<number_of> pages), <number_of> commands, <appl_pid_and_node>


Modified pages can be displaced from the data cache to the data area, because not all of the data used by the applications can be held in the data cache.

If the size of the data cache is sufficient, the physical writing is delayed until the next savepoint and then is done asynchronously. Cache displacements, however, use synchronous writes and reads, and should be avoided if possible.

This phenomenon is almost unavoidable if load times (data import) are long, since the volume of imported data is usually much larger than the size of the data cache.

User Response

Increase the size of the data cache.


More Information

Relevant  DB-Analyzer Files
Helpful with ...
DBAN_CACHES.csv Successful and unsuccessful accesses to caches, and also hit rates 
DBAN_SAVEPOINTS  Information about savepoints
DBAN_IOTHREADS.csv Find more information about duration of physical read/write. 
DBAN_IO.csv Statistics about the numbers of I/O operations. 
SAP Note
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Expert Sessions (Link to trainings)
Content / Helpful with ...
Session 10: SAP MaxDB LoggingInformation about savepoint handling.
Session 17: SAP MaxDB Shadow Page Algorithm Provides information about what happens during a savepoint. 
Session 26: SAP MaxDB I/O Concept General information about the I/o concept.
Documentation (links)
Helpful with ...
Concepts of the Database System
Working Memory Areas
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