[Pdns-users] PDNS Recursor on Debian / Low performance !!!URGENT!!!!

Stefan Schmidt zaphodb at zaphods.net
Mon Feb 7 10:04:00 UTC 2011

On Mon, Feb 07, 2011 at 09:48:30AM +0000, Maroon Ibrahim wrote:
> Thanks Stefan...
> SO, you just recommend to play only with max-cache-entries...? 
> I have 4GB ram and Xeon CPU.

Let me put it this way:
Using a standard recursor.conf you should not need to tweak much more than the
max-cache-entries and bind to specific addresses to get pretty decent
performance from the recursor. 
However since v. 3.2 of the recursor there is also the max-packetcache-entries
setting to be tuned.
I would recommend setting both of these to 1000000 entries for starters.
They are per thread btw. meaning that depending on the number of cores you
will end up with potentially more memory usage than the 4GB available to you.

> is it possible to cache the entries on disk?? is it recommended also?

This is not possible with PowerDNS recursor, nor is it recommended. I forgot
the exact reasoning for this however - it had something to do with the need to
run through all the entries in the cache and adjust their TTL value upon
loading them. I think Bert has pondered implementing this in the past and gave
up on the thought.


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