Can't start postgres server, SHMMAX too small When I try to start the postgres server with sudo /etc/init.d/postgresql start I get this error:


  Starting PostgreSQL 8.4 database server: mainThe PostgreSQL server
  failed to start. Please check the log output: 2012-10-31 17:52:46 EDT
  FATAL: could not create shared memory segment: Invalid argument
  2012-10-31 17:52:46 EDT DETAIL: Failed system call was
  shmget(key=5432001, size=188080128, 03600). 2012-10-31 17:52:46 EDT
  HINT: 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 188080128 bytes), reduce
  PostgreSQL's shared_buffers parameter (currently 19200) and/or its
  max_connections parameter (currently 103). 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 documentation contains more
  information about shared memory configuration. ... failed!


What should I do here?  Shared_buffers is actually set to 150MB and max_connections is actually set to 100 in the only postgresql.conf file available to it...

I don't know if the request is unusually high, SHMMAX unusually low, or if postgres grabbed some config parameters from the Aether, either seem equally likely...

What am I supposed to make of this, and how do I fix it?
This question has been asked many times. Try a search. Or Google.

This chapter of the manual deals with it comprehensively.