In a RAC architecture is easy to move from ASMM to AMM
SQL> conn / as sysdba
Connected.
SQL> alter system set memory_max_target=9G scope=spfile sid='*';
System altered.
SQL> alter system set memory_target=8G scope=spfile sid='*';
System altered.
SQL> alter system set sga_target=0 scope=spfile sid='*';
System altered.
SQL> alter system set pga_aggregate_target=0 scope=spfile sid='*';
System altered.
Then for each instance do a stop and a start:
srvctl stop instance -d dbora -i dbora2
srvctl start instance -d dbora -i dbora2
srvctl stop instance -d dbora -i dbora1
srvctl start instance -d dbora -i dbora1
SQL> conn / as sysdba
Connected.
SQL> alter system set memory_max_target=9G scope=spfile sid='*';
System altered.
SQL> alter system set memory_target=8G scope=spfile sid='*';
System altered.
SQL> alter system set sga_target=0 scope=spfile sid='*';
System altered.
SQL> alter system set pga_aggregate_target=0 scope=spfile sid='*';
System altered.
Then for each instance do a stop and a start:
srvctl stop instance -d dbora -i dbora2
srvctl start instance -d dbora -i dbora2
srvctl stop instance -d dbora -i dbora1
srvctl start instance -d dbora -i dbora1
Anyway, if you try to increase even more memory_max_target, at restart you might get the following error:
srvctl start instance -d dbora -i dbora2
PRCR-1013 : Failed to start resource ora.dbora.db
PRCR-1064 : Failed to start resource ora.dbora.db on node node-2
CRS-5017: The resource action "ora.dbora.db start" encountered the following error:
ORA-00845: MEMORY_TARGET not supported on this system
This error is generated by the size of memory chunks in memory allocation that is different depending on the size of memory allocated.
A workaround might be to decrease MEMORY_MAX_TARGET or increase also MEMORY_TARGET
