[Pdns-users] question about PDNS - performance

Owen Borseth owen at domainsite.com
Tue Feb 22 21:08:34 UTC 2005

We have four servers using PDNS with a shared MySQL back end. Two 
servers average ~610 qps with ~2ms q/a latency and the other two average 
~210 qps with less than 1ms q/a latency. Our cache hit rate is about 96% 
on all servers. We haven't had any performance issues using PDNS to date.

This is with PDNS running on IBM blades with 1GB of memory and a single 
2.4GHz Xeon. Memory usage for PDNS is minimal, less than 400K, and CPU 
usage averages ~2.5%.

I would have to say that I have never been happier with a piece of 
software in my life than I am with PDNS. It's fast, simple, and 
relatively maintenance free once you get it up and running.

There is a caveat to all of this. We were never able to get it running 
decent on a dual proc kernel. We tried everything we could think of but 
it would cap out at about 30 qps. I haven't tried it with the latest 2.6 
kernel but performance is fine enough so I'm not too concerned.

- Owen

Dan Clark wrote:

> I recently tried powerdns and was pretty astounded that it couldn't 
> keep up with my 30 odd zones.
> It could be misconfiguration but I can't get debugging/logging to 
> work, unless I start the daemon using /etc/init.d/pdns monitor
> Once I did get it all going, queries took too long to return results 
> and reverse lookup zones didn't seem to work. Then after a day in 
> service the box would only answer queries from nslookup/dig on the box 
> itself and no longer from the interweb as it would time out before it 
> could answer the query.
> I'm lost really, why would it do this on a fresh install with very 
> little zones?
> Cheers
> Dan Clark
> Technical Director
> Synaptic Ltd
> Michiel van Es wrote:
>> Hi,
>> I am thinking to switch our Bind DNS to Powerdns.
>> How fast is Powerdns?
>> We are hosting zones with a large amount of answers/queries per 
>> minute (at least  20.000 answers per.minute - 500 queries p/m)
>> This is for 1 zone..we are having 3 or 4 of this kind of customers 
>> which are having such a large DNS load.
>> Can PDNS with Mysql (gmysql backend) handle this amount of load easily?
>> What is the MAX?
>> I know it is also a hardware  issue but we are currently running this 
>> load on dual p 3 800 Mhz 512 MB Ram and 2 18,2 GB SCSI disks).
>> Thanks for some answers/benchmarks results/experiences..
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