In addition to tuning the various Postgres config knobs you may need to
look at how your AWS server is set up. If your load is causing an IO
stall then *symptoms* of this will be lots of locks...
You have quite a lot of memory (60G), so look at tuning the
vm.dirty_background_ratio, vm.dirty_ratio sysctls to avoid trying to
*suddenly* write out many gigs of dirty buffers.
Your provisioned volumes are much better than the default AWS ones, but
are still not hugely fast (i.e 1000 IOPS is about 8 MB/s worth of
Postgres 8k buffers). So you may need to look at adding more volumes
into the array, or adding some separate ones and putting pg_xlog
directory on 'em.
However before making changes I would recommend using iostat or sar to
monitor how volumes are handling the load (I usually choose a 1 sec
granularity and look for 100% util and high - server hundred ms -
awaits). Also iotop could be enlightening.
Regards
Mark
On 02/04/13 11:35, Armand du Plessis wrote:
It's on Amazon EC2 -
* cc2.8xlarge instance type
* 6 volumes in RAID-0 configuration. (1000 PIOPS)
60.5 GiB of memory
88 EC2 Compute Units (2 x Intel Xeon E5-2670, eight-core)
3370 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
EBS-Optimized Available: No**
API name: cc2.8xlarge
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