Oracle Database Discussions

hi gurus,

3 node rac 10.2.0.4 serving a packaged application.

Top 5 timed events in awr shown as


Event=CPU time
Waits=
Time(s)=1,950
Avg Wait(ms)
% Total Call Time=45.3
Wait Class

Event=gc cr multi block request
Waits= 6,551,055
Time(s)= 1,396
Avg Wait(ms)=0
% Total Call Time=38.9
Wait Class= Cluster

Event=db file scattered read
Waits= 186,295
Time(s)= 719
Avg Wait(ms)=4
% Total Call Time=18.2
Wait Class= User I/O

Event=db file parallel read
Waits= 43,383
Time(s)= 241
Avg Wait(ms)=6
% Total Call Time= 5.9
Wait Class= User I/O
Event= log file sync
Waits= 71,064
Time(s)= 83
Avg Wait(ms)=1
% Total Call Time= 3.1
Wait Class= Commit



db_block_size=8KB
db_file_multiblock_read_count = default setting of 128

question:
are the high wait values of gc cr multi block request and db file scattered read are due to db_file_multiblock_read_count?
if that's the case, is there a way to find optimum value for db_file_multiblock_read_count?
or any other findings please?

experts, appreciate your valuable help

thanks in advance,
charles