I'm guessing the high bursts are checkpoints. Can you check your log files for pg and see if you are getting warnings about checkpoint frequency? You can get some mileage here by increasing wal files.
Nope, nothing in the log. I have set: wal_buffers=128 checkpoint_segments=128 checkpoint_timeout=3000 which I thought was rather generous. Perhaps I should set it even higher for the loads?
Have you determined that pg is not swapping? try upping maintenance_work_mem.
maintenance_work_mem = 524288 ... should I increase it even more? Doesn't look like pg is swapping ...
What exactly is your architecture? is your database server direct attached to the san? if so, 2gb/4gb fc? what san? have you bonnie++ the san? basically, you can measure iowait to see if pg is waiting on your disks.
I'm currently running bonnie++ with the defaults ... should I change the execution to better mimic Postgres' behavior? RHEL 4.3 x86_64 HP DL585, 4 Dual Core Opteron 885s 16 GB RAM 2x300GB 10K SCSI320, RAID10 HP MSA1000 SAN direct connected via single 2GB Fibre Channel Arbitrated Loop 10x300GB 10K SCSI320, RAID10
