Supporting large caches (> 4GB) in BIND?

sthaug at nethelp.no sthaug at nethelp.no
Mon Feb 15 17:47:45 UTC 2010


> > Have you *measured* the hit rate of your current BIND resolvers
> > with different cache sizes? How many queries per second are you
> > trying to support?
> 
> We do about 3,000 queries/second typically. I haven't measured query
> -rates vs cache sizes. We've had max-cache-size set to 3GB for a long
> time, but the process never exceeded 2GB until recent crashes prompted 
> recompilation as 64-bit.

We do around 5500 q/s at 85% cache hit rate with a CNS process of just
under one Gigabyte. This is not BIND but the statistics might still be
relevant. 

If you feel that more memory is a worthwhile use of resources then by
all means go for it. Personally I wouldn't consider it until my hit
rate dropped to significantly less than 70%. However, the hit rate is
of course dependent on your customers and their query profile, and it
is entirely possible that our two cases are significantly different
(mine is from the perspective of a commercial ISP).

Steinar Haug, Nethelp consulting, sthaug at nethelp.no



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