DB6: How to deactivate file system caching in V9.5
[91 v9.5] [buffered] [caching] [cio] [deactivate] [dio] [file] [I/O] [skydriverxp v9.5] [system] [v9.5]
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Symptom
You want to deactivate file system buffered I/O on DB2 objects.
Other terms
file system caching, file system buffered I/O, dio, cio
Reason and Prerequisites
DB2 has own buffer pools in memory. When file system buffered I/O is used for table spaces, a page might be buffered on both DB2 buffer and OS file system buffer. Duplicate buffering consumes additional CPU and memory resources unnecessarily and it may lead to non-optimal I/O performance due to resource bottlenecks.
Data on file system buffer might be lost in case the operating system terminates abnormally. Therefore, log files are recommended not to be buffered at a file system buffer level, but should be read/written directly from/to disks.
Solution
In order to deactivate file system buffered I/O, implement the following:
1. DMS/SMS table spaces in file systems
- set the “FILE SYSTEM CACHING = NO” attribute for all table spaces by
“ALTER TABLESPACE
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