FATAL: could not create shared memory segment:

ERROR

Starting PostgreSQL 8.3 database server: mainThe PostgreSQL server failed to start. Please check the log output: 2010-09-29 11:49:05 UTC LOG: could not load root certificate file "root.crt": no SSL error reported 2010-09-29 11:49:05 UTC DETAIL: Will not verify client certificates. 2010-09-29 11:49:05 UTC FATAL: could not create shared memory segment: Cannot allocate memory 2010-09-29 11:49:05 UTC DETAIL: Failed system call was shmget(key=5433001, size=29368320, 03600). 2010-09-29 11:49:05 UTC HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory or swap space. To reduce the request size (currently 29368320 bytes), reduce PostgreSQL's shared_buffers parameter (currently 3072) and/or its max_connections parameter (currently 103). The PostgreSQL documentation contains more information about shared memory configuration. failed!

SOLUTION

Here in error itself clearly specified the solution what we have to do..
just reduce the shared buffer ( shared memory ) size which value defined in RESOURCE USAGE part of the postgresql.conf file

in unix system path is /etc/postgresql/8.3/main/postgresql.conf

#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------

# - Memory -

shared_buffers = 24MB # min 128kB or max_connections*16kB
# (change requires restart)
#temp_buffers = 8MB

--------------------------------------------------------------------------------
once edit this value restart the server..