POSTGRESQL error Could not create shared memory segment: Cannot allocate memory

Recently my client database has restarted and thrown the below error. FATAL: could not create shared memory segment: Cannot allocate memory DETAIL: Failed system call was shmget(key=5433001, size=5616156672, 03600). HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory or swap space, or exceeded your kernel's SHMALL parameter. You can either reduce the request size or reconfigure the kernel with larger SHMALL. To reduce the request size (currently 5616156672 bytes), reduce PostgreSQL's shared memory usage, perhaps by reducing shared_buffers or max_connections. The PostgreSQL documentation contains more information about shared memory configuration. LOG: database system was interrupted; last known up at 2017-06-07 08:10:13 BST FATAL: the database system is starting up FATAL: the database system is starting up How can I resolve this issue?