Re: Amazon High I/O instances

I agree 1GB is a lot, I played around with that value, but it hardly makes
a difference. Is there a plateau in how that value affects query
performance ? On a master DB, I would set it low and raise as necessary,
but what would be a good average value on a read-only DB with same spec and
max_connections ?

I will run a test again and let you know how is the IO. Might also run
bonnie++ to see if the raid performs as expected...

Sébastien

On Wed, Sep 12, 2012 at 6:17 PM, François Beausoleil
<francois(at)teksol(dot)info>wrote:

>
> Le 2012-09-12 à 17:08, Sébastien Lorion a écrit :
>
> > As you can see, I am nowhere near the results John mentioned for a
> 10,000 scale (about 8000 tps) and I am not sure why. My instance setup and
> configuration should be ok, but I am far from an expert (a startup founder
> has to wear many hats...), I simply followed advice found in Greg Smith
> book and what I read on the net. So, if anyone can offer insight as to why
> the performance is not as good as expected, please let me know ..
> >
> > I did not terminate the AMI yet, so I can do more testing and/or try
> suggestions to improve the results. I will also try to run the benchmarks
> again on a pure RAID1 configuration with fsync off, which I will use for
> read-only databases.
>
> I wonder if work_mem is too high? That's 1 GB per connection (max), but
> still a lot of RAM. Might want to try with more reasonable values, such as
> 16MB to 64MB.
>
> What are the iostat / vmstat numbers during the test?
>
> Bye,
> François