Testing Direct I/O

Hi,

The DB is Oracle 9i on an HP-UX 11.11 system. My question concerns direct I/O.

I've read numerous papers and vendor documentation (Oracle and HP) on the merits of bypassing the HP buffer cache (i.e. direct i/o).

However, I'd like to test the results of actually using direct i/o. In order to not re-invent the wheel, I was wondering if anyone had performed similar testing?

I saved and executed a few benchmark SQL statements pre-direct i/o, is this enough? Can I simply re-exexcute these benchmark statements?

What metrics should I be focusing on to "quantify" direct i/o benefit in my environment?

What I don't want to do is switch to direct i/o and have performance decrease (i.e. temp TS space was de-buffered) or not understand what/why performance decreased...

Thanks much!

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