IpcMemoryCreate: shmget(key=5432001, size=647168, 03600) failed: Invalid argument

This error usually means that PostgreSQL's request for a shared memory
segment exceeded your kernel's SHMMAX parameter.  You can either
reduce the request size or reconfigure the kernel with larger SHMMAX.
To reduce the request size (currently 647168 bytes), reduce
PostgreSQL's shared_buffers parameter (currently 24) and/or
its max_connections parameter (currently 4).

If the request size is already small, it's possible that it is less than
your kernel's SHMMIN parameter, in which case raising the request size or
reconfiguring SHMMIN is called for.

The PostgreSQL Administrator's Guide contains more information about
shared memory configuration.