-- Demo case: How to identify which SHM segment is used by an Oracle instance
-- Date: 13-05-2019
-- Demo case run with Oracle version: 12.2.0.1 & 18.3.0.0.180717

-- List of Oracle instances on one host
[root@OEL ~]# ps -ef | grep -i lgwr
oracle    6137     1  0 19:03 ?        00:00:00 ora_lgwr_T122DB
oracle    6540     1  0 19:03 ?        00:00:00 ora_lgwr_T183DB


-- List of all SHM segments
[root@OEL ~]# ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 360448     oracle     600        4096       0                       
0x00000000 393217     oracle     600        4096       0                       
0x00000000 425986     oracle     600        4096       0                       
0x00000000 458755     oracle     600        4096       0                       
0x00000000 491524     oracle     600        4096       0                       
0xceb4cad8 524293     oracle     600        12288      50                      
0x00000000 557062     oracle     600        8663040    100                     
0x00000000 589831     oracle     600        2919235584 50                      
0x00000000 622600     oracle     600        8114176    50                      
0xedd61d60 655369     oracle     600        16384      50            


-- Identify SHM segments related to instance T122DB
T122DB [oracle@OEL ~]$ sysresv -l T122DB

IPC Resources for ORACLE_SID "T122DB" :
Maximum shared memory segment size (shmmax): 4398046511104 bytes
Total system shared memory (shmall): 17592186044416 bytes
Total system shared memory count (shmmni): 4096
*********************** Dumping ipcs output ********************

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 360448     oracle     600        4096       0                       
0x00000000 393217     oracle     600        4096       0                       
0x00000000 425986     oracle     600        4096       0                       
0x00000000 458755     oracle     600        4096       0                       
0x00000000 491524     oracle     600        4096       0                       
0xceb4cad8 524293     oracle     600        12288      53                      
0x00000000 557062     oracle     600        8663040    100                     
0x00000000 589831     oracle     600        2919235584 50                      
0x00000000 622600     oracle     600        8114176    50                      
0xedd61d60 655369     oracle     600        16384      50                      

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0xde4e6e28 720898     oracle     600        152       
0xde4e6e29 753667     oracle     600        152       
0xde4e6e2a 786436     oracle     600        152       
0xcbc477a0 917509     oracle     600        250       
0xcbc477a1 950278     oracle     600        250       

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    

*********************** End of ipcs command dump **************
 

***************** Dumping Resource Limits(s/h) *****************
core file size                         0 KB/UNLIMITED         
data seg size                     UNLIMITED/UNLIMITED         
scheduling priority                    0 KB/0 KB              
file size                         UNLIMITED/UNLIMITED         
pending signals                       44 KB/44 KB             
max locked memory                    128 GB/128 GB            
max memory size                   UNLIMITED/UNLIMITED         
open files                            64 KB/64 KB             
POSIX message queues                 800 KB/800 KB            
real-time priority                     0 KB/0 KB              
stack size                            32 MB/32 MB             
cpu time                          UNLIMITED/UNLIMITED         
max user processes                    16 KB/16 KB             
virtual memory                    UNLIMITED/UNLIMITED         
file locks                        UNLIMITED/UNLIMITED         

***************** End of Resource Limits Dump ******************
Maximum map count configured per process:  65530
Total /dev/shm size: 1140850688 bytes, used: 956301312 bytes
Shared Memory:
ID		KEY
393217  	0x00000000
425986  	0x00000000
458755  	0x00000000
491524  	0x00000000
360448  	0x00000000
524293  	0xceb4cad8
Semaphores:
ID		KEY
720898  	0xde4e6e28
753667  	0xde4e6e29
786436  	0xde4e6e2a
Oracle Instance alive for sid "T122DB"


-- Identify SHM segments related to instance T183DB
T183DB [oracle@OEL ~]$ sysresv -l T183DB

IPC Resources for ORACLE_SID "T183DB" :
Maximum shared memory segment size (shmmax): 4398046511104 bytes
Total system shared memory (shmall): 17592186044416 bytes
Total system shared memory count (shmmni): 4096
*********************** Dumping ipcs output ********************

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 360448     oracle     600        4096       0                       
0x00000000 393217     oracle     600        4096       0                       
0x00000000 425986     oracle     600        4096       0                       
0x00000000 458755     oracle     600        4096       0                       
0x00000000 491524     oracle     600        4096       0                       
0xceb4cad8 524293     oracle     600        12288      50                      
0x00000000 557062     oracle     600        8663040    101                     
0x00000000 589831     oracle     600        2919235584 51                      
0x00000000 622600     oracle     600        8114176    51                      
0xedd61d60 655369     oracle     600        16384      51                      

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0xde4e6e28 720898     oracle     600        152       
0xde4e6e29 753667     oracle     600        152       
0xde4e6e2a 786436     oracle     600        152       
0xcbc477a0 917509     oracle     600        250       
0xcbc477a1 950278     oracle     600        250       

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    

*********************** End of ipcs command dump **************
 

***************** Dumping Resource Limits(s/h) *****************
core file size                         0 KB/UNLIMITED         
data seg size                     UNLIMITED/UNLIMITED         
scheduling priority                    0 KB/0 KB              
file size                         UNLIMITED/UNLIMITED         
pending signals                       44 KB/44 KB             
max locked memory                    128 GB/128 GB            
max memory size                   UNLIMITED/UNLIMITED         
open files                            64 KB/64 KB             
POSIX message queues                 800 KB/800 KB            
real-time priority                     0 KB/0 KB              
stack size                            32 MB/32 MB             
cpu time                          UNLIMITED/UNLIMITED         
max user processes                    16 KB/16 KB             
virtual memory                    UNLIMITED/UNLIMITED         
file locks                        UNLIMITED/UNLIMITED         

***************** End of Resource Limits Dump ******************
Maximum map count configured per process:  65530
Total /dev/shm size: 1140850688 bytes, used: 956301312 bytes
Shared Memory:
ID		KEY
589831  	0x00000000
622600  	0x00000000
557062  	0x00000000
655369  	0xedd61d60
Semaphores:
ID		KEY
917509  	0xcbc477a0
950278  	0xcbc477a1
Oracle Instance alive for sid "T183DB"