Question regarding db_file_scattered_read
- From: "Johnson, George" <GJohnson@xxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 18 Jul 2005 14:24:25 +0100
I have a DB on a Solaris box, the system that is almost at 100%
utilisation, I'm not overly worried as no one is complaining, yet. I am
simply trying to identify where the resources are being consumed, partly
curiosity and partly in the hope of preventing a potential future problem.
I have been over the wait stats and found that the system spends
it's time, almost exclusively, making users wait on db_file_scattered_read,
about 30% of their session time, in fact. However the OS reports hardly any
I/O wait time, the system resources are being used up by user CPU. I believe
the entire SGA is little too small, I am wondering if the scattered_read
waits are a result of the SGA and/or buffer cache being too small or would a
buffer cache that is too small, more likely result in buffer_busy_waits or
have I got my thinking completely backside-about-face!? All the notes I can
find relate db_file_scattered_read to an I/O performance problem, which from
what I can tell from the OS, I don't seem to have.
Any pointers in the direction I should start off in next, would be
greatly appreciated.
Rgds
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