During installation of Oracle you can encounter typical error commonly know by DBAs

ORA-00845: MEMORY_TARGET not supported on this system

Oracle is using for automatic memory management Linux shared segments. Usually they are too small but you can modify it on-the-fly.

Just modify entry in “/etc/fstab” to have persistent settings between reboot of your machine. Here shared segments are set to 2500M.

tmpfs   /dev/shm   tmpfs  size=2500M  0 0

remount it

mount -o remount tmpfs

and verify

mount | grep tmpfs
tmpfs on /dev/shm type tmpfs (rw,size=2500M)

to see what is using shared segments run following command

[oracle@oel6 ~]$ ipcs -m

------ Shared Memory Segments --------
key        shmid      owner    perms  bytes  nattch  status      
0x00000000 158433298  oracle   640    4096   0      
0x00000000 158466067  oracle   640    4096   0      
0x00000000 158498836  oracle   640    4096   0      
0x9d984658 158531605  oracle   640    12288  49

Have a fun 🙂
Tomasz