[Pdns-users] TinyDNS Backend questions

Fri Aug 31 14:49:42 UTC 2012

Hello,

guardian parameter is not present in the default configuration file.
I plan to check the performance but the first step is too ensure all is 
working the same then if we improve the performance it is a bonus.

I will get back to you with more details.

Regards,
Francois

On 2012-08-31 14:05, Ruben d'Arco wrote:
> Hi,
>
> On Fri, Aug 31, 2012 at 01:30:39PM +0200, xbgmsharp wrote:
>> Hello,
>>
>> Thanks for the reply.
>> I use PowerDNS's SVN version as TinyDNS backend is not ship by
>> default in the package.
>> So I believe, I have this patch apply,
>> http://wiki.powerdns.com/trac/changeset/2622
>
> Yep!
>
>> I will apply the patch from github.
>> According to my first test using dnsperf, PowerDNS with TinyDNS
>> backend seen faster than TinyDNS himself.
>> The biggest concern is stability to avoid PowerDNS to crash due to
>> weird data or too many data.
>> The file contains 26643 entries and errors.
>
> PowerDNS can run with a guardian, so it would never crash and burn
> without launching again.
> This can be set using the guardian=yes option in the config file (i'm
> not sure if it's a default).
>
> The patch mentioned on github should avoid errors whenever there are
> errors in the data.cdb file.
> All the times this happend, we could trace it down to an error in the
> data file, which results in wrong
> data in the data.cdb file. Lot's of those errors are mentioned here:
> 
> http://homepage.ntlworld.com/jonathan.deboynepollard/FGA/djbdns-problems.html#tinydns-data-semantic-error
> But, as you're a tinydns user, you'll probably already know about 
> these :-)
>
>> It use the default configuration from PowerDNS, I am sure it could
>> be improve by tunning PowerDNS.
>
> The performance improvement probably comes from caching that PowerDNS 
> has.
> http://doc.powerdns.com/performance-settings.html might be nice to
> read to gain some more understanding
> of this.
>
>> The system is Ubuntu 12.04 compile with gcc 4.6.3 on x86_64.
>> The hardware is a one Intel(R) Xeon(R) CPU X3330 @2.66GHz with 4
>> Cores and 4096M System RAM.
>> It is not the production system but should give us a nice idea.
>> I need to go deeper in the testing, but so far so good.
>>
>> PowerdNS with tinyDNS backend.
>> Statistics:
>>
>>   Queries sent:         26608
>>   Queries completed:    15416 (57.94%)
>>   Queries lost:         11192 (42.06%)
>>
>>   Response codes:       NOERROR 15415 (99.99%), NXDOMAIN 1 (0.01%)
>>   Average packet size:  request 45, response 61
>>   Run time (s):         565.866733
>>   Queries per second:   27.243164
>>
>>   Average Latency (s):  0.035546 (min 0.033069, max 0.056192)
>>   Latency StdDev (s):   0.001457
>>
>> TinyDNS
>> Statistics:
>>
>>   Queries sent:         26608
>>   Queries completed:    11835 (44.48%)
>>   Queries lost:         14773 (55.52%)
>>
>>   Response codes:       NOERROR 11834 (99.99%), NXDOMAIN 1 (0.01%)
>>   Average packet size:  request 45, response 129
>>   Run time (s):         745.820314
>>   Queries per second:   15.868433
>>
>>   Average Latency (s):  0.049470 (min 0.041367, max 0.078622)
>>   Latency StdDev (s):   0.004388
>>
>> Regards,
>> Francois
>
>
> Regards,
> 	Ruben
>
>> On 2012-08-31 10:18, Ruben d'Arco wrote:
>> >Hi Francois,
>> >
>> >The tinydnsbackend is marked experimental because 3.1 is the first
>> >release that has the backend.
>> >PowerDNS needs some 'out in the field' validation that the backend 
>> is
>> >working correctly.
>> >Please provide feedback, as we could then remove the experimental
>> >flag!
>> >
>> >We know one user who uses it with a data.cdb file > 70M. That user
>> >also has identified some issues, one
>> >important issue is fixed in
>> >http://wiki.powerdns.com/trac/changeset/2622
>> >You can either apply the patch yourself, or take PowerDNS's SVN
>> >version to have this resolved.
>> >This patch is strongly recommended!
>> >
>> >The user also reported that PowerDNS handles errors in the data.cdb
>> >file different from tinydns.
>> >I've added an configuration option to allow the behaviour to be
>> >configurable, the patch for that can be found here:
>> >
>> 
>> >https://github.com/cyclops1982/powerdns/compare/master...tinydns2.diff
>> >This patch is only useful if your data.cdb file is not a 100%
>> >correct. Something that can be resolved by
>> >making sure your data file is correct before running tinydns-data.
>> >
>> >The scenario you're planning (move from dbjdns to powerdns and then
>> >change backend) is a scenario we've heard before
>> >and partially why the backend was created - the master mode that 
>> the
>> >backend provides should help you with this.
>> >
>> >Kind regards,
>> >        Ruben d'Arco
>> >
>> >
>> >
>> >On Fri, Aug 31, 2012 at 09:53:58AM +0200, xbgmsharp wrote:
>> >>Hello,
>> >>
>> >>According to the documentation
>> >>(http://doc.powerdns.com/tinydnsbackend.html), the TinyDNS backend
>> >>is marked as experimental!
>> >>It this statement still true?
>> >>
>> >>We are currently using tinydns and djbdns in all our 
>> infrastructure.
>> >>We are thinking in moving to Powerdns to support new feature.
>> >>However before doing a big move, we would rater make the move in
>> >>multiple step.
>> >>The first step would be to use Powerdns with TinyDNS backend.
>> >>The second step would be to move from TinyDNS backend to a 
>> database
>> >>backend.
>> >>This second step require a rewrite of our DNS tools and it will 
>> take
>> >>longer.
>> >>
>> >>Our data.cdb is file is around 18M.
>> >>
>> >>Do you think it is safe to use Powerdns with TinyDNS backend in
>> >>production?
>> >>
>> >>Regards,
>> >>Francois
>> >>
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