When try to start up an Oracle database, the below errors occur:
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 * 480 / 4096 = 125829120
2) Edit /etc//etc/sysctl.conf
kernel.shmall = 125829120 3) Apply the change
# sysctl -p 4) Check shmall value after change.
# sysctl -A | grep shmall5) Start up database successfully.
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 * 480 / 4096 = 125829120
2) Edit /etc//etc/sysctl.conf
kernel.shmall = 125829120 3) Apply the change
# sysctl -p 4) Check shmall value after change.
# sysctl -A | grep shmall5) Start up database successfully.