-- Demo case: SHM identical alignment 
-- Date: 13-05-2019
-- References: MOS ID #1399908.1 - Why Multiple Shared Memory Segments are Created From 11.2.0.3
-- Info: Each shared memory segment making up the SGA only contains sub-areas with an identical alignment requirement
-- Demo case from Oracle version: 10.2.0.5 & 18.3.0.0.180717

-- 10.2.0.5
SQL> show parameter sga_target
NAME				                 TYPE	     VALUE
------------------------------------ ----------- ------------------------------
sga_target			                 big integer 2800M

T10DB [oracle@OEL ~]$ ipcs -ma
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x9ab64f4c 0          oracle     640        2938109952 21                      
------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0x4f625578 229378     oracle     640        154       
------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    


-- 18.3.0.0.180717
SQL> show parameter sga_target
NAME				                 TYPE	     VALUE
------------------------------------ ----------- ------------------------------
sga_target			                 big integer 2800M

T183DB [oracle@OEL ~]$  ipcs -ma
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 32768      oracle     600        8663040    128                     
0x00000000 65537      oracle     600        2919235584 64                      
0x00000000 98306      oracle     600        8114176    64                      
0xedd61d60 131075     oracle     600        16384      64                      
------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0xcbc477a0 360450     oracle     600        250       
0xcbc477a1 393219     oracle     600        250       
------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages