In this section are various notes/examples relating to Unix (primarily AIX).

Filesystems

• View
• Mount/Unmount
• Users Using
• Space Used In
• Change Size

Performance

• IO
• Memory

Miscellaneous

• Vim/Vi
• Fifo special files
• Useful finds

In this section are various notes/examples relating to Oracle

• Estimate Rollback Time
• Maximum mbrc

You can use the following to work out the maximum value of
db_file_multiblock_read_count for your system

Set mbrc to a silly value:

alter session set db_file_multiblock_read_count = 32767;

Trace a full table scan on a large table:

alter session set events '10046 trace name context forever, level 8';

select /*+ full(t) noparallel(t) nocache(t) */ count(*) from big_table t;

Then look in trace file generated. Query needn't finish - you can interrupt it
once the trace file contains the required info.

Look in the trace file for stat for 'db file scattered read' wait entries and the
p3 value is the maximum mbrc Oracle is able to achieve - regardless of the init
parameter setting.

WAIT #3: nam='db file scattered read' ela= 6 p1=11 p2=120393 p3=64
                                                             ^^^^^