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<number> of <number_of> read ahead requests could not be fulfilled, configured number of parallel requests (MaxDataAreaReadAheadRequests): <number>


To improve I/O performance a read ahead (prefetch) mechanism is provided allowing the parallel import of data pages from the disks to the cache. If a high number of request could not be fulfilled this will impact the overall I/O performance.

User Response

If there is a high failing rate check the task configuration in the system, especially the distribution of server tasks.

Check the disk performance.

More Information

Relevant  DB-Analyzer Files
Helpful with ...
DBAN_IO_PREFETCH.csv IgnoredRequests, Requests 
SAP Notes 
1327874 - FAQ: SAP MaxDB Read Ahead/Prefetch Provides information about the different prefetch mechanisms.
1672994 - SAP MaxDB: Configuration of server tasks 
Expert Sessions
Content / Helpful with ...
Session 29: SAP MaxDB: Improvements in I/O Handling 7.9 and Prefetch MechanismsProvides general information about the different concepts of prefetch mechanisms. 
Documentation (links) 
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