[Pdns-dev] feature request (persistent cache for recursor)
zaphodb--pdns-dev at zaphods.net
Tue Apr 24 18:37:13 CEST 2007
On Tue, Apr 24, 2007 at 09:52:31AM +0300, Igor Popov wrote:
> Hi, all!
> PowerDNS has a very good recursor, but after startup it perfomance is poor,
> persistent cache (dump the cache from a running recursor and load dumped
> cache at startup) can really improve situation.
I run a cluster of recursors behind a loadbalancer and while its true what you
say, performance of the recursor is much better with a full cache, i don't
really seem to have a need for that feature as my caches tend to get filled up
again rather quickly and i never saw any significant performance impact on our
caching dns performance due to recursor restarts.
I wonder what your cache size might be to let you feel any performance impacts,
mine range from 1 to 2 million entries.
Also implementing something like what you proposed bears the problem that by
the time you load the cache from a file its TTLs will already be outdated and
thus you end up serving old and probably even bogus data which i think was the
reason i was told BIND does not incorporate that function.
Computers make very fast, very accurate mistakes.
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