When I try to start postmaster, I get IpcSemaphoreCreate errors. Why?
If the error message is IpcSemaphoreCreate: semget failed (No space left on device) then your kernel is not configured with enough semaphores. Postgres needs one semaphore per potential backend process. A temporary solution is to start postmaster with a smaller limit on the number of backend processes. Use -N with a parameter less than the default of 32. A more permanent solution is to increase your kernel’s SEMMNS and SEMMNI parameters. Inoperative semaphores can also cause crashes during heavy database access. If the error message is something else, you might not have semaphore support configured in your kernel at all. See the PostgreSQL Administrator’s Guide for more detailed information about shared memory and semaphores.
