Rather large LA

Hi,

I have a database server that's part of a web stack and is experiencing prolonged load average spikes of up to 400+ when the db is restarted and first accessed by the other parts of the stack and has generally poor performance on even simple select queries.

There are 30 DBs in total on the server coming in at 226GB. The one that's used the most is 67GB and there are another 29 that come to 159GB.

I'd really appreciate it if you could review my configurations below and make any suggestions that might help alleviate the performance issues. I've been looking more into the shared buffers to the point of installing the contrib module to check what they're doing, possibly installing more RAM as the most used db @ 67GB might appreciate it, or moving the most used DB onto another set of disks, possible SSD.

PostgreSQL 9.0.4
Pgbouncer 1.4.1

Linux 2.6.18-238.9.1.el5 #1 SMP Tue Apr 12 18:10:13 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

CentOS release 5.6 (Final)

4 x Intel Xeon-NehalemEX E7540-HexCore [2GHz] ( 24 physical cores )
32GB DDR3 RAM
1 x Adaptec 5805 Z SATA/SAS RAID with battery backup
4 x Seagate Cheetah ST3300657SS 300GB 15RPM SAS drives in RAID 10
1 x 500GB 7200RPM SATA disk

Postgres and the OS reside on the same ex3 filesystem, whilst query and archive logging go onto the SATA disk which is also ext3.

name | current_setting
--------------------------------+-------------------------------------------------------------------------------------------------------------------
version | PostgreSQL 9.0.4 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48), 64-bit
archive_command | tar jcf /disk1/db-wal/%f.tar.bz2 %p
archive_mode | on
autovacuum | off
checkpoint_completion_target | 0.9
checkpoint_segments | 10
client_min_messages | notice
effective_cache_size | 17192MB
external_pid_file | /var/run/postgresql/9-main.pid
fsync | off
full_page_writes | on
lc_collate | en_US.UTF-8
lc_ctype | en_US.UTF-8
listen_addresses |
log_checkpoints | on
log_destination | stderr
log_directory | /disk1/pg_log
log_error_verbosity | verbose
log_filename | postgresql-%Y-%m-%d_%H%M%S.log
log_line_prefix | %m %u %h
log_min_duration_statement | 250ms
log_min_error_statement | error
log_min_messages | notice
log_rotation_age | 1d
logging_collector | on
maintenance_work_mem | 32MB
max_connections | 1000
max_prepared_transactions | 25
max_stack_depth | 4MB
port | 6432
server_encoding | UTF8
shared_buffers | 8GB
superuser_reserved_connections | 3
synchronous_commit | on
temp_buffers | 5120
TimeZone | UTC
unix_socket_directory | /var/run/postgresql
wal_buffers | 10MB
wal_level | archive
wal_sync_method | fsync
work_mem | 16MB

Pgbouncer config

[databases]
* = port=6432
[pgbouncer]
user=postgres
pidfile = /tmp/pgbouncer.pid
listen_addr =
listen_port = 5432
unix_socket_dir = /var/run/postgresql
auth_type = trust
auth_file = /etc/pgbouncer/userlist.txt
admin_users = postgres
stats_users = postgres
pool_mode = session
server_reset_query = DISCARD ALL;
server_check_query = select 1
server_check_delay = 10
server_idle_timeout = 5
server_lifetime = 0
max_client_conn = 4096
default_pool_size = 100
log_connections = 1
log_disconnections = 1
log_pooler_errors = 1
client_idle_timeout = 30
reserve_pool_size = 800

Thanks in advance

Richard