/dev/shm过小导致ORA-00845错误解决方法

The workaround, if you encounter the ORA-00845 error, is to increase the /dev/shm
mountpoint size.
For example:
# mount -t tmpfs shmfs -o size=7g /dev/shm
To make this change persistent across system restarts, add an entry in /etc/fstab
similar to the following:
shmfs /dev/shm tmpfs size=7g 0

Starting with Oracle Database 11g, the Automatic Memory Management feature
requires more shared memory (/dev/shm)and file descriptors. The size of the shared
memory must be at least the greater of the MEMORY_MAX_TARGET and MEMORY_
TARGET parameters for each Oracle instance on the computer. If the MEMORY_MAX_
TARGET parameter or the MEMORY_TARGET parameter is set to a non-zero value, and
an incorrect size is assigned to the shared memory, it results in an ORA-00845 error at
startup. On Linux systems, if the operating system /dev/shm mount size is too small
for the Oracle system global area (SGA) and program global area (PGA), it will result
in an ORA-00845 error.
The number of file descriptors for each Oracle instance must be at least
512*PROCESSES. The limit of descriptors for each process must be at least 512. If file
descriptors are not sized correctly, you will see an ORA-27123 error from various
Oracle processes and potentially Linux Error EMFILE (Too many open
files)in non-Oracle processes.
To determine the amount of shared