undersized SGA

[Roshan]

Oracle Database 12.1.0.2 (RAC 2 nodes)
Solaris 11.4
RAM on each node: 64 GB
CPU: 4 cores each

Hello Erman,

can you please advise if I should procure additional memory on each node since I see 'UNDERSIZED SGA' in AWR report. The amount of free memory is 3-4 GB on OS on first node.
awrrpt_04Nov2019.html
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Regards,

Joe

[Roshan]

In case RAM needs not to be increased, by how much can I increase SGA?

NAME                 TYPE        VALUE

-------------------- ----------- -----

pga_aggregate_limit  big integer 9000M

pga_aggregate_target big integer 3726M

 

NAME                         TYPE        VALUE  

---------------------------- ----------- -------

allow_group_access_to_sga    boolean     FALSE  

lock_sga                     boolean     FALSE  

pre_page_sga                 boolean     TRUE  

sga_max_size                 big integer 11200M

sga_target                   big integer 11200M

unified_audit_sga_queue_size integer     1048576

[ErmanArslansOracleBlog]

Check your Memory usage by using free command.
you can use sar utility for an historical memory consumption report as well.

The report says : Increase the size of the SGA by setting the parameter "sga_target" to 12600 M
So start with 12600M first..
The reports also complains about the PGA size. As you know, pga_aggregate_target is not a limit, but lots of parameters are derived from that.. you may increase this one as well..

But first you need to determine your memory consumption..
also note that, after increasing the values, get the same report once again and see if those "undersized...." recommendations are cleared.

One last thing, in RAC we set the same sga and pga values for each node. So if you want to increase SGA or PGA, you will increase it in both nodes. That means, you need to make your memory consumption analysis on both nodes..(because PGA consumption may differ according to the nodes)