[Pdns-users] TinyDNS Backend questions

Fri Aug 31 12:05:12 UTC 2012

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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