I have worked on this issue with both IBM and Oracle. This is the final version of my investigation and what I implement on the databases here. I see you mostly used some of the reference I did.
- Mount FS with CIO for DFs, redo, and archive dest. Do NOT use with CFs and OH.
- On 9i, change file system options to 'setall' - Do NOT use JFS with DIO or JFS with large file enabled. - Enable large page support - disable VMM from steeling pages from the SGAWhat is your current setting for the filesystem options? If still at default, change to 'setall' dynamically and see if you can see the direct IO calls now.
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