When trying to start up an Oracle database, the below errors occur:

ORA-27125: unable to create shared memory segment
Linux-x86_64 Error: 28: No space left on device
Additional information: 3773
Additional information: 3221225472

CAUSE

Kernel parameter kernel.shmall is not set properly.

RESOLUTION

Make sure kernel.shmall is given the appropriate value.

1)  Calculate the value of shmall.

getconf PAGE_SIZE

4096
Shmall=total size of the SGAs /PAGE_SIZE.
If the total SGA size is 480GB, then it would be 1024 * 1024 * 1024 * 32 / 4096 = 8388608  

2) Edit /etc/sysctl.conf
kernel.shmall = 8388608 

3) Apply the change
# sysctl -p  

4) Check shmall value after change.
# sysctl -A | grep shmall

5) Start up database successfully.

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