I need your advice - Mailing list pgsql-general

Good day to all ...

I hope any one can give me an advice ... to optimize my database...

im having a problem when i'm backing up my DB and also using vacuum for my
DB...
my CPU load goes up.... and no one can use my DB... most of the transaction
comes from web server..

I just need ur good advice ...

thank you

please check my postgresql.conf
--
#
#
# Connection Parameters
#
tcpip_socket = true
#ssl = false

max_connections = 300
superuser_reserved_connections = 100

port = 5432
#hostname_lookup = false
#show_source_port = false

#unix_socket_directory = ''
#unix_socket_group = ''
#unix_socket_permissions = 0777 # octal

#virtual_host = ''

#krb_server_keyfile = ''


#
# Shared Memory Size
#
shared_buffers = 600  # min max_connections*2 or 16, 8KB each
#max_fsm_relations = 1000 # min 10, fsm is free space map, ~40 bytes
#max_fsm_pages = 10000  # min 1000, fsm is free space map, ~6 bytes
#max_locks_per_transaction = 64 # min 10
#wal_buffers = 8  # min 4, typically 8KB each

#
# Non-shared Memory Sizes
#
#sort_mem = 1024  # min 64, size in KB
#vacuum_mem = 8192  # min 1024, size in KB


#
# Write-ahead log (WAL)
#
#checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
#checkpoint_timeout = 300 # range 30-3600, in seconds
#
#commit_delay = 0  # range 0-100000, in microseconds
#commit_siblings = 5  # range 1-1000
#
#fsync = true
#wal_sync_method = fsync # the default varies across platforms:
#    # fsync, fdatasync, open_sync, or open_datasync
#wal_debug = 0   # range 0-16


#
# Optimizer Parameters
#
enable_seqscan = true
enable_indexscan = true
enable_tidscan = true
enable_sort = true
enable_nestloop = true
enable_mergejoin = true
enable_hashjoin = true

effective_cache_size = 1000 # typically 8KB each
random_page_cost = 4  # units are one sequential page fetch cost
cpu_tuple_cost = 0.01  # (same)
cpu_index_tuple_cost = 0.001 # (same)
cpu_operator_cost = 0.0025 # (same)

default_statistics_target = 10 # range 1-1000

#
# GEQO Optimizer Parameters
#
geqo = true
geqo_selection_bias = 2.0 # range 1.5-2.0
geqo_threshold = 11
geqo_pool_size = 1024  # default based on tables in statement,
    # range 128-1024
geqo_effort = 1
geqo_generations = 0
geqo_random_seed = -1  # auto-compute seed


#
# Message display
#
#server_min_messages = notice # Values, in order of decreasing detail:
    #   debug5, debug4, debug3, debug2, debug1,
    #   info, notice, warning, error, log, fatal,
    #   panic
#client_min_messages = notice # Values, in order of decreasing detail:
    #   debug5, debug4, debug3, debug2, debug1,
    #   log, info, notice, warning, error
#silent_mode = false

log_connections = true
#log_pid = false
log_statement = true
log_duration = true
log_timestamp = true

#log_min_error_statement = panic # Values in order of increasing severity:
     #   debug5, debug4, debug3, debug2, debug1,
     #   info, notice, warning, error, panic(off)

#debug_print_parse = false
#debug_print_rewritten = false
#debug_print_plan = false
#debug_pretty_print = false

#explain_pretty_print = true

# requires USE_ASSERT_CHECKING
#debug_assertions = true


#
# Syslog
#
syslog = 2   # range 0-2
syslog_facility = 'LOCAL0'
syslog_ident = 'postgres'


#
# Statistics
#
show_parser_stats = false
show_planner_stats = false
show_executor_stats = false
show_statement_stats = false

# requires BTREE_BUILD_STATS
#show_btree_build_stats = false


#
# Access statistics collection
#
stats_start_collector = false
stats_reset_on_server_start = false
stats_command_string = false
stats_row_level = false
stats_block_level = false


#
# Lock Tracing
#
#trace_notify = false

# requires LOCK_DEBUG
#trace_locks = false
#trace_userlocks = false
#trace_lwlocks = false
#debug_deadlocks = false
#trace_lock_oidmin = 16384
#trace_lock_table = 0


#
# Misc
#
autocommit = true
#dynamic_library_path = '$libdir'
#search_path = '$user,public'
#datestyle = 'iso, us'
#timezone = unknown  # actually, defaults to TZ environment setting
#australian_timezones = false
#client_encoding = sql_ascii # actually, defaults to database encoding
#authentication_timeout = 60 # 1-600, in seconds
#deadlock_timeout = 1000 # in milliseconds
#default_transaction_isolation = 'read committed'
#max_expr_depth = 10000  # min 10
#max_files_per_process = 1000 # min 25
#password_encryption = true
#sql_inheritance = true
#transform_null_equals = false
#statement_timeout = 0  # 0 is disabled, in milliseconds
#db_user_namespace = false



#
# Locale settings
#
# (initialized by initdb -- may be changed)
LC_MESSAGES = 'en_US.UTF-8'
LC_MONETARY = 'en_US.UTF-8'
LC_NUMERIC = 'en_US.UTF-8'
LC_TIME = 'en_US.UTF-8'

-----------------

here is my diskspace..
/dev/sdb1              3526172   1132784   2214268  34% /
/dev/sda1               248895      8796    227249   4% /boot
none                   2005700         0   2005700   0% /dev/shm
/dev/md0              65757260  50992580  11424376  82% /var
/dev/sdc1             17409840  13521548   3003916  82% /backup
----------------