Re: What value Oracle uses for db_cache_size when making decision on direct path reads if db_cache_size isn't set?

On Mon, 18 Aug 2014 01:11:49 -0700, vsevolod afanassiev wrote:

> strace allows to see system calls, for example, if I trace DBWR process
> when opening database I see something like that:
>
> open("/db01/oracle/oractrl/control_01.ctl",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 15
> open("/db02/oracle/oractrl/control_02.ctl",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 16
> open("/db01/oracle/oradata/system_01.dbf",
> O_RDONLY|O_DIRECT|O_LARGEFILE) = 17
> open("/db01/oracle/oradata/system_01.dbf",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 17
> open("/db01/oracle/oradata/undo_01_01.dbf",
> O_RDONLY|O_DIRECT|O_LARGEFILE) = 18
> open("/db01/oracle/oradata/undo_01_01.dbf",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 18
> open("/db02/oracle/oradata/sysaux_01.dbf",
> O_RDONLY|O_DIRECT|O_LARGEFILE) = 19
> open("/db02/oracle/oradata/sysaux_01.dbf",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 19
> open("/db02/oracle/oradata/tools_01.dbf", O_RDONLY|O_DIRECT|O_LARGEFILE)
> = 20 open("/db02/oracle/oradata/tools_01.dbf",
> O_RDWR|O_SYNC|O_DIRECT|O_LARGEFILE) = 20
>
>
> How do you use output of strace to see internal calculations done by
> Oracle?

You should be looking for the "read" calls, used by Oracle to read the files.

-- 
Mladen Gogala
The Oracle Whisperer
http://mgogala.byethost5.com