Re: Poor Performance on Oracle9i - 9.2.0.7

On Sun, 7 May 2006 12:43:18 +0200, "Ralph Ganszky" <rg_at_web.de> wrote:

>But may be you agree that on a 24GB Server it should be possible to allocate
>more than 2.78 GB for the SGA.

approx 8Gb following Oracle's own guidelines. The actual memory consumption for the user Oracle would be much more, as this would include memory allocated by dedicated server sessions. I've seen configurations, where all hitratio's (it was hitratio age then) were superb, but the server was suffocating from paging .
Mind you, I recently reviewed a configuration using Toad, where the customers DBA *did* allocate 50 percent of memory to Oracle. He overruled me, as he didn't trust my explanation of the effects on the system.
Toad was complaining about buffer cache wastage: the buffer cache was simply too big. Just because of various LRU and/or Touch Count algorithms, no one will ever reach a 100 percent hit ratio.

More is not always better.
Tuning by throwing memory at the problem, without tuning statements, is doomed to fail miserably.

--
Sybrand Bakker, Senior Oracle DBA