Problem
SQL> show parameter memory
NAME TYPE VALUE
------------------------------------ ----------- --------
hi_shared_memory_address integer 0
memory_max_target big integer 3152M
memory_target big integer 3152M
shared_memory_address integer 0
SQL> alter system set memory_max_target=8G scope=spfile;
System altered.
SQL> alter system set memory_target=8G scope=spfile;
System altered.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system
Solution
[root@prod ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 754G 42G 674G 6% /
tmpfs 3.9G 88K 3.9G 1% /dev/shm
/dev/shm mount point size must be greater than or equal to value of MEMORY_TARGET parameter
So Increase the size of /dev/shm mount point
[root@prod ~]# umount -l /dev/shm/
[root@prod ~]# mount -t tmpfs shmfs -o size=8g /dev/shm
[root@prod ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 754G 42G 674G 6% /
shmfs 8.0G 0 8.0G 0% /dev/shm
SQL> startup
ORACLE instance started.
Total System Global Area 8551575552 bytes
Fixed Size 2215064 bytes
Variable Size 4093641576 bytes
Database Buffers 4429185024 bytes
Redo Buffers 26533888 bytes
Database mounted.
Database opened.
SQL> show parameter memory
NAME TYPE VALUE
------------------------------------ ----------- ---------
hi_shared_memory_address integer 0
memory_max_target big integer 8G
memory_target big integer 8G
shared_memory_address integer 0