[Pdns-users] PowerDNS cannot handle the load?

Mike Benoit mikeb at netnation.com
Wed Apr 9 21:04:08 UTC 2003

On Wed, 2003-04-09 at 12:39, Stephane Bortzmeyer wrote:
> On Wednesday 9 April 2003, at 9 h 9, 
> Mike Benoit <mikeb at netnation.com> wrote:
> > What was your cache timeout set to? How often did you query the same
> > records? 
> The defaults:
> cache-ttl=20
> query-cache-ttl=20
> negquery-cache-ttl=60

If your not updating records often, I recommend bumping these waaay up.
We use:


> A PC with two 2Ghz processors, 1 Gbytes of RAM and a GigaEthernet card. It 
> runs the Debian operating system, "unstable" branch, with the Linux kernel 
> 2.4.20.

Something is definately wrong if you can only do ~200queries/sec with
this hardware. If I recall correctly, Bert was seeing in excess of
10,000 queries/sec with a TDB backend on similar hardware. 

> > We can easily handle 500+ queries/sec on a
> > PIII-866 with a PostgreSQL backend. 
> May be the size of the zone is the issue. What is yours? We used a zone of 
> 150,000 domains.

This should make no difference to the SQL backend, it may to the bind
backend, I'm not sure.

> This is much better. No more hanging of the server, a performance which is almost the same as BIND9 (identical for the two backends). It means that the cache works fine. But it is not very realistic :-)
>   Queries per second:   7037.402371 qps

Yeah, this tells us that PDNS itself can perform very well. I would
concentrate on tweeking Postgres or trying MySQL. Obviously PDNS can
only be as fast as the database backend, (with cache disabled) so tuning
the database is very important. 

Did you turn fsync off in Postgres? Increased its memory allocation? Are
you sure there are indexes on the PDNS tables? Have you run "vacuum
analyze" on both tables recently? 

Unfortunately PostgreSQL comes configured out of the box for
portability/stability in mind, therefore it requires quite a bit of
tuning to get the performance up to par. 

I would be interested in seeing results from a MySQL backend. 

Best Regards,
Mike Benoit
NetNation Communications Inc.
Systems Engineer
Tel: 604-684-6892 or 888-983-6600
 Disclaimer: Opinions expressed here are my own and not 
 necessarily those of my employer

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