Increase SGA in Oracle 10g

Question

Hi everyone,
I am Ann. I am not a DBA, because the main DBA and Developer is on maternity leave have to step up to look after an Oracle Application Forms and Reports and Oracle database (version 10.1).
Recently, people complaints the apps is slow.
So I open the Enterprise Manager, and check the Performance Adviser, it shows one issue
Finding          The buffer cache was undersized causing significant additional read I/O.
Impact (minutes)          5.31
Impact (%)     
13.13
The recommendation is Increase SGA target size by increasing the value of parameter "sga_target" by 928 M. (there is a button Implement next to the message).
The findings path is
The buffer cache was undersized causing significant additional read I/O.
13.13     
Wait class "User I/O" was consuming significant database time.     16.27     
About the server, we use OpenSuse. I also log into the server as root.
Type free command to get info about memory and here is the details
borg:~ # free
total used free shared buffers cached
Mem: 6101512 6001288 100224 0 180376 4636256
-/+ buffers/cache: 1184656 4916856
Swap: 12586916 1728548 10858368
I just want to know is it safe to run the implement button to increase the SGA target size.
I know that I have to shutdown and restart the instance.
Many thanks,
Ann

Answer 1

>
I just want to know is it safe to run the implement button to increase the SGA target size.
>
You shouldn't do anything until
1. You confirm that there is, in fact, a problem
2. You determine exactly what the problem is
3. You determine the cause, or causes, of the problem
4. You identify, and rank, possible solutions to the problem
5. You test possible solutions in a dev/text environment to make sure your process works as expected.
6. You script a method to 'undo' any changes you make
>
Recently, people complaints the apps is slow.
>
So what! People always complain that apps are slow. While it's fine to take note of that don't make a knee-jerk reaction to it.
Gather more information.
1. Slow in what way? entering data? running reports? batch jobs?
2. Slow when? first thing in the morning? mid-day when all users are on the system? all the time?
3. How long has it been slow? Just started? A couple of days? a few weeks?
4. What does the main DBA say about the reported slowness? Have you called to ask? Why not? They are on maternity leave not climbing the alps or Himalayas. Call them and ask them if they were aware of reported problems.
5. Did you ask the main DBA what you should look at? Why not?
Tell us more information. What are the memory parameters now?
Open a sql*plus session and then run and post the results of
1. SHOW PARAMETER SGA_TARGET
2. SHOW SGA
3. SHOW PARAMETER POOL