Server Not Running

Dear all,

Today I do some changes in postgresql.conf &shmmax parameters as :

root~# cat /proc/sys/kernel/shmall
8388608
root~# cat /proc/sys/kernel/shmmax
4294967296

max_connections = 80
shared_buffers = 2048MB
work_mem = 32MB
maintenance_work_mem = 512MB
fsync=off
full_page_writes=off
synchronous_commit=off
checkpoint_segments = 32
checkpoint_completion_target = 0.7 effective_cache_size = 4096MB

Now when I start the server , it fails as

root(at)sun-cloud:/opt/PostgresPlus/8.4SS/data# /etc/init.d/postgresql-8.4
start
Starting PostgreSQL 8.4:
waiting for server to
start...............................................................could
not start server
PostgreSQL 8.4 did not start in a timely fashion, please see
/opt/PostgresPlus/8.4SS/data/pg_log/startup.log for details

My startup.log is empty & ps command shows no server running before :

root~# ps aux | grep 5432
root 1840 0.0 0.0 7620 880 pts/0 S+ 11:14 0:00 grep
--color=auto 5432

Do anybody knows what went wrong

Thanks